Pharmaceutical compositions and methods of inhibiting H-1 and H-2 histamine receptors

ABSTRACT

Pharmaceutical compositions and methods of inhibiting H-1 and H-2 histamine receptors by administering an antihistamine and an H-2 histamine receptor inhibitor. Exemplary of the antihistamine in the compositions and methods of this invention is mepyramine and exemplary of the H-2 histamine receptor inhibitor is N-cyano-N&#39;-methyl-N&#34;-[2-((4-methyl-5-imidazolyl)-methylthio)ethyl]guanidine.

This application is a continuation-in-part of Serial No. 349,151 filedApr. 9, 1973, now U.S. Pat. No. 3,894,151.

This invention relates to pharmaceutical compositions having H-1 and H-2histamine receptor inhibiting activity and methods of inhibiting H-1 andH-2 histamine receptors. The compositions comprise an antihistamine andan H-2 histamine receptor inhibitor. The compositions and methods ofthis invention have utility in producing anti-inflammatory andcardiovascular activity and for treating shock where low blood pressureis associated with elevated levels of histamine.

In the following co-pending U.S. patent applications:

Ser. No. 80,818 filed Oct. 14, 1970 U.S. Pat. No. 3,759,944;

Ser. No. 80,819 filed Oct. 14, 1970 U.S. Pat. No. 3,736,331;

Ser. No. 330,548 filed Feb. 8, 1973 abandoned;

Ser. No. 310,302 filed Nov. 29, 1972 U.S. Pat. No. 3,868,457;

Ser. No. 80,794 filed Oct. 14, 1970 U.S. Pat. No. 3,734,924;

Ser. No. 335,853 filed Feb. 26, 1973 abandoned;

Ser. No. 306,948 filed Nov. 15, 1972 abandoned;

Ser. No. 312,438 filed Dec. 6, 1972 U.S. Pat. No. 3,808,336;

Ser. No. 230,451 filed Feb. 29, 1972 abandoned;

Ser. No. 290,584 filed Sept. 20, 1972 abandoned;

Compounds are described which demonstrate an antagonism to those actionsof histamine which are not inhibited by the compounds such as mepyraminewhich are normally referred to as "antihistamines". The latter compoundshave been referred to as H-1 antagonists, and, more recently, we havedesignated the former as H-2 antagonists (See Black et al. Nature 1972,236,385).

Black et al., cited above, page 390, column 2, state the following:

"Mepyramine has been defined as an H₁ -receptor antagonist¹ andburimamide has now been defined as an H₂ -receptor antagonist. Usedalone, burimamide can antagonize those responses to histamine, such asstimulation of acid gastric secretion, which cannot be blocked bymepyramine; histamine apparently activates H₂ -receptors to producethese effects. Histamine responses, such as hypotension which can onlybe partially antagonized by mepyramine alone can be completely blockedby mepyramine and burimamide given in combination; both H₁ and H₂-receptors seem to be activated by histamine to produce effects of thiskind." Thus, H-1 histamine receptors are those histamine receptors whichare inhibited by mepyramine and H-2 histamine receptors are thosehistamine receptors which are not inhibited by mepyramine but areinhibited by burimamide. For the purpose of the present specificationH-2 antagonist compounds described and claimed in our said co-pendingapplications will be referred to as compounds of class A and the H-1antagonist compounds such as mepyramine will be referred to as compoundsof class B.

The H-2 antagonist compounds of class A comprise the following groups:

a. Thioureas of the general formula I: ##STR1## wherein A is such thatthere is formed together with the carbon and nitrogen atoms shown anunsaturated heterocyclic basic nucleus, preferably having five or sixatoms, e.g., imidazole, pyridine, thiazole, or 1,2,4-triazole; X ishydrogen, lower alkyl, halogen or lower alkylthio; n is from 3 to 6; andR is hydrogen, lower alkyl, benzoyl or substituted or unsubstitutedphenylethyl.

Particularly preferred compounds of this group are those wherein A issuch that, with the carbon and nitrogen atoms shown, it forms animidazole or thiazole ring. Further preferred features, one or more ofwhich may be present in the compounds of this group are that n should be4, that X should be hydrogen or a halogen such as bromo and that Rshould be alkyl (particularly methyl) or hydrogen.

Specific preferred compounds of group (a) areN-methyl-N'-[4-(4(5)-imidazolyl)butyl]thiourea, N-[4-(4(5)-imidazolyl)butyl]thiourea, N-methyl-N'-[4-(2-thiazolyl)butyl]thiourea andN-methyl-N'-[4-(4-bromo-5-imidazolyl)butyl]thiourea.

b. Compounds of the formula II: ##STR2## wherein A is such that there isformed together with the carbon atom shown an unsaturated heterocyclicnucleus, which comprises at least one nitrogen atom and may comprisefurther hetero atoms such as sulphur and oxygen; X₁ is hydrogen, loweralkyl, hydroxyl, trifluoromethyl, benzyl, halogen, amino or ##STR3## X₂is hydrogen or, when X₁ is lower alkyl, lower alkyl or halogen; k is 0to 2 and m is 2 or 3, provided that the sum of k and m is 3 or 4; Y isoxygen, sulphur or NH; E is oxygen, sulphur or NR₂ ; R₁ is hydrogen,lower alkyl, benzoyl or di-lower alkylamino lower alkyl; and R₂ ishydrogen, nitro or cyano.

Examples of specific unsaturated heterocyclic nuclei are imidazole,pyridine, thiazole, isothiazole, oxazole, isoxazole, pyrazole, triazole,thiadiazole, pyrimidine, pyrazine, pyridazine, benzimidazole or5,6,7,8-tetrahydro-[1,5-a]pyridine, particularly preferred beingimidazole, thiazole, isothiazole and pyridine. Further preferredfeatures, one or more of which may be present in the compounds of thisgroup are that k should be 1 and m should be 2, Y should be sulphur, Eshould be sulphur or N-cyano, X₂ should be hydrogen and X₁ should bemethyl, hydrogen, bromo, amino or hydroxyl.

Specific preferred compounds of group (b) areN-methyl-N'-[2-((5-methyl-4-imidazolyl)methylthio)ethyl]thiourea,N-methyl-N'-[2-((4-imidazolyl)methylthio)ethyl]thiourea, andN-cyano-N'-methyl-N"-[2-((4-methyl-5-imidazolyl)methylthio)ethyl]guanidine.

c. Amidine derivatives of the formula III: ##STR4## wherein A is suchthat there is formed together with the carbon and nitrogen atom shown anunsaturated heterocyclic basic nucleus having five or six atoms,; X ishydrogen, hydroxyl, trifluoromethyl, amino, halogen, lower alkyl orlower alkylthio; n is from 2-5; R₁ is lower alkyl; phenyl optionallymono-substituted by halogen, hydroxy or nitro; benzyl; loweralkythio-lower alkyl; --NHR₃ or --SR₄ ; R₂ is hydrogen, an alkyl groupcontaining from 1-4 carbon atoms, phenyl, benzyl, or, when R₁ is --NHR₃,cyano or nitro; R₃ is hydrogen, methyl, benzyl or amino; and R₄ is analkyl group having 1 to 6 carbon atoms, an alkenyl or alkynyl grouphaving 2 to 6 carbon atoms or (CH₂)_(m) Z where m is 1 to 3 and Z isphenyl optionally mono-substituted by halogen, hydroxy or nitro;hydroxy; di-lower alkylamino; cyano; carboxy; phenoxy; benzhydryloxy; orimidazolyl and wherein R₃ or R₄ may, with R₂, form a five membered ringwith the adjacent atoms.

As in the case of group (b) above, examples of specific unsaturatedheterocyclic nuclei are imidazole, pyridine, thiazole, isothiazole,oxazole, isoxazole, pyrazole, triazole, thiadiazole, pyrimidine,pyrazine and pyridazine of which imidazole, thiazole, isothiazole andpyridine are particularly preferred. Further preferred features, one ormore of which may be present in the compounds of this group are that nshould be from 3 to 5, that X should be hydrogen, methyl, bromo, aminoor hydroxyl and that R₁ should be amino, methylamino or --SR₄.

Specific preferred compounds of group (c) areS-(2-phenoxyethyl)-N-[3-(4-imidazolyl)propyl]isothiourea,S-(p-chlorobenzyl)-N-[3-(4-imidazolyl)propyl]isothiourea,S-ethyl-N-[3-(4-imidazolyl)propyl]isothiourea and4-(3-guanidinopropyl)imidazole

d. Isothioureas of the formula IV: ##STR5## wherein n is from 2 to 4; Ais such that it forms with the carbon and nitrogen atom shown anunsaturated heterocyclic basic nucleus having five or six atoms; R₁ ishydrogen or lower alkyl; R₂ is hydrogen, lower alkyl, amino or benzyl orR₁ and R₂ together form an ethylene bridge; and X is hydrogen, halogenor benzyl.

In the preferred compounds of group (d) the unsaturated heterocyclicnucleus is imidazole, pyridine, pyrazole or triazole and furtherpreferred features, one or more of which may be present in the compoundsof this group are that X should be hydrogen and that R₁ and R₂ should behydrogen or methyl.

Specific preferred compounds of group (d) are: N₁N'-dimethyl-S-[2-(4(5)-imidazolyl)ethyl]isothiourea andS-[4-(4(5)-imidazolyl)butyl]isothiourea.

e. Amidines of the formula V. ##STR6## wherein n is 3 or 4.

f. The pharmaceutically acceptable acid addition salts of all thecompounds set out in groups (a) to (e) above.

A particular group of guanidine compounds which are H-2antagonists ofclass A and which are the H-2 histamine receptor inhibitors of thepharmaceutical compositions and methods of the present applicationconsits of 4-(3-guanidinopropyl)-imidazole and a compound represented byformula II above wherein A is such that there is formed together withthe carbon atom shown an imidazole, thiazole, isothiazole or pyridinering; X₁ is hydrogen, lower alkyl, halogen, amino or hydroxyl; X₂ ishydrogen; k is 1; m is 2; E is NR₂ ; R₁ is hydrogen or lower alkyl andR₂ is hydrogen, nitro or cyano, or a pharmaceutically acceptable acidaddition salt thereof.

The compounds of class B comprise all those compounds generallyrecognised and known as antihistamines, all of which compounds thereforeantagonise histamine H-1 receptors. The preferred compounds of class Bare those which have the minimal sedating affect on the central nervoussystem and the duration of whose effect is of the same order as that ofthe class A compound with which it is included in the composition ofthis invention. Such preferred compounds include mapyramine,mebrophenhydramine, promethazine, diphenhydramine, chlorpheniramine,triprolidene, antazoline, bromodiphenydramine, parabromdylamine,carbinoxamine, cyproheptadine, chlorcyclizine, dimethindene,diphenylpyraline, dimethothiazine methdilazine, trimeprazine,mebhydroline, methapyrilene, phenindamine, pheniramine, phenyltoloxamineand pyrrobutamine.

The compounds of class B which are found to be particularly suitable aremepyramine, mebrophenhydramine and promethazine.

According to the present invention we provide a pharmaceuticalcomposition which comprises a compound of class A and a compound ofclass B together with a pharmaceutically acceptable diluent or carrier.

The compounds of class A may be prepared by methods which are describedin the co-pending applications listed hereabove. These methods aredescribed as follows:

Thus, a suitable method for the production of compounds of group (a)involves the treatment of an amine of formula VI: ##STR7## wherein A, Xand n have the same significance as in formula I with an isothiocyanateof formula R'N=C=S wherein R' is lower alkyl or substituted orunsubstituted aroyl or aralkyl followed in the case where R' is benzoylby hydrolysis to the compound of formula I wherein R is hydrogen.

The starting material for the production of compounds of group (b) is acompound of formula VII: ##STR8## wherein X₁, X₂, A, k, m and Y have thesame significance as in formula II. This substance is reacted with acompound of the formula VIII:

    r.sub.1 -- n = c = e

formula viii

wherein R₁ has the same significance as in formula II and E is sulphuror oxygen or with a compound of the formula IX: ##STR9## wherein R₂ hasthe same significance as in formula II.

The compounds of group (c) may be produced from the amine of formula VIwherein A, X and n have the same significance as in formula III.Reaction thereof with a compound of formula X or of formula XI:##STR10## wherein R₂ and R₃ have the same significance as in formula IIIand R₁ is lower alkyl, substituted or unsubstituted phenyl, aralkyl oralkylthioalkyl yields respectively products of formula III wherein R₁ isNHR₃ or is lower alkyl, substituted or unsubstituted phenyl, aralkyl oralkylthioalkyl. To produce compounds of formula III wherein R₁ is SR₄,the amine of formula VI is first converted to the thiourea of formula Iwherein X, A and n have the same significance as in formula III and Rhas the same significance as R₂ in formula III and this thiourea is thenreacted with a compound of formula XII:

    r.sub.4 y

formula xii

wherein R₄ has the same significance as in formula III and Y is halogenor hydroxy.

The compounds of group (d) may be formed from a substance of the formulaXIII: ##STR11## wherein A, X and n have the same significance as informula IV and Y is hydroxy or halogen by treatment thereof with athiourea of formula XIV: ##STR12## wherein R₁ and R₂ have the samesignificance as in formula IV.

Finally, the compounds of group (e) can be prepared from a nitrile offormula XV: ##STR13## wherein n is 3 or 4 by reaction thereof withmethanol or ethanol to give an imino - ether of formula XVI: ##STR14##wherein n is 3 or 4 and R is methyl or ethyl which on treatment withammonia yields the required compound of formula V.

The preferred compounds of class B are, as stated above, all well knownand readily available antihistamine compounds.

The acute anti-inflammatory action of the compositions according to thepresent invention may be demonstrated by means of the biologicalscreening tests which are commonly employed for this purpose. One suchscreening test is the rat paw oedema test wherein the swelling of arat's paw caused by the injection of certain substances such ashistamine, the histamine-releasing agents known as compound 48/80 and5-HT, yeast, kaolin and carageenin into the plantar surface is measured(e.g. plethysmographically) both in untreated control rats and in ratswhich have been treated sub-cutaneously with the anti-inflammatorycomposition. Another such test is the guinea-pig U-V erythema testwherein the depilated skin of a guinea-pig is exposed for a standardtime to U.V. radiation and the intensity of the resultant erythema incontrol and treated animals is assessed over a period of hours.

The compositions according to the invention have been assessed on boththese tests and, as will be apparent from the experimental datahereinafter, have shown marked anti-inflammatory action at dosescontaining about 500 micromoles per kilogram of the H-2 antagonist ofclass A and from about 50 to 100 micromoles per kilogram of theantihistamine of class B. These doses were given by sub-cutaneousinjection. It will be noted, where individual compounds of class A andclass B have been also tested separately, that the anti-inflammatoryaction shown by each compound alone is much less than that shown by thecombination.

The cardiovascular activity of the compositions according to the presentinvention has been assessed in anaesthetised cats, dogs and rabbits. Inthe anaesthetised cat or dog, histamine has long been known to causehypotension. When administered intravenously in relatively large doses(e.g., greater than 0.02 micromoles/Kg.), this effect has been found tobe refractory to treatment with the H-1 antagonist compounds of class B(Folkow et al., Acta Physiol. Scand. 1948, 15 264). We have found thatthe H-2 antagonist compounds of Class A have no inhibiting influence onthis effect but we have now found that the compositions of the presentinvention containing from 5 to 100 micromoles per kilogram of the H-2antagonist of class A and from 10 to 50 micromoles per kilogram of theantihistamine of class B, given intravenously, can completely inhibitthis histamine-induced hypotension. In the anaesthetised rabbit,intravenously administered histamine may produce pressor, depressor orbiphasic changes in blood pressure depending on the dose and theanaesthetic used. The H-1 antagonist compounds of class B are known toreverse the pressor responses to depressor responses (see Staub, Ann.Inst. Pasteur, 1939, 63 400) and we have shown that the H-2 antagonistcompounds of class A potentiate the pressor responses. The compositionsof our invention containing from 1 to 50 micromoles per kilogram of theH-2 antagonist of class A and from 1 to 10 micromoles per kilogram ofthe antihistamine of class B, given intravenously, completely abolishedboth pressor and depressor responses.

The compositions of the present invention also have utility inantagonising other pharmacological actions where both H-1 and H-2histamine receptors are involved. Thus they can be useful in combatingthe effects of certain types of shock, for example, the shock-like stateproduced by bacterial endotoxins. By a mechanism which is thought toinvolve histamine, these endotoxins, which arepolysaccharide-protein-lipid complexes released on bacterialdisintegration, cause a profound fall in arterial blood pressure.Anaesthetised rats, which had previously been treated with thecompositions of our invention containing from 10 to 100 micromoles perkilogram of the antihistamine and from 100 to 1000 micromoles perkilogram of the H-2 antagonist, when given intravenously 5 mg./Kg. ofsuch an endotoxin showed a significantly smaller fall in blood pressurethan untreated control rats.

The compositions of the present invention, in addition to the activecompounds of class A and class B, comprise a pharmaceutically acceptablecarrier. Advantageously the compositions will be made up in a dosageunit form appropriate to the desired mode of administration. Thepharmaceutical carrier employed may be, for example, either a solid orliquid. Exemplary of solid carriers are lactose, terra alba, sucrose,talc, gelatin, agar, pectin, acacia, magnesium stearate, stearic acidand the like. Exemplary of liquid carriers are syrup, peanut oil, oliveoil, water and the like. Other pharmacologically active compounds may incertain cases be included in the pharmaceutical compositions.

A wide variety of pharmaceutical forms can be employed. Thus, if a solidcarrier is used, the preparation can be tableted, placed in a hardgelatin capsule in powder or pellet form, or in the form of a troche orlozenge. The amount of solid carrier will vary widely but preferablywill be from about 25 mg. to about 1 gm. If a liquid carrier is used,the preparation may be in the form of syrup, emulsion, soft gelatincapsule, sterile injectable liquid such as an ampoule, or an aqueous ornonaqueous liquid suspension.

The pharmaceutical compositions are prepared by conventional techniquesinvolving procedures such as mixing, granulating and compressing ordissolving the ingredients as appropriate to the desired preparation.

The active ingredients will be present in the composition in aneffective amount to inhibit both H-1 and H-2 histamine receptors. Theroute of administering may be orally, topically or may be parenterallye.g., sub-cutaneously or intravenously.

Preferably, each dosage unit will contain the active ingredients ofclass A (H-2 antagonist) in an amount of from about 50 mg to about 500mg and the active ingredient of class B (antihistamine) in an amount offrom about 30 mg. to about 250 mg.

The active ingredients will preferably be administered in equal dosesthree to six times per day. The daily dosage regimen will preferably befrom about 500 mg to about 3000 mg.

For therapeutic use, the pharmacologically active compounds in thepharmaceutical composition of our invention will normally beadministered in the basic form or in the form of an addition salt with apharmaceutically acceptable acid. Such addition salts include those withhydrochloric, hydrobromic, hydriodic, sulphuric, picric and maleicacids.

Advantageously the composition will be made up in a dosage formappropriate to the desired mode of administration, for example as atablet, capsule, injectable solution or as a cream or ointment fortopical administration.

The invention is illustrated but in no way limited by the followingexamples.

EXAMPLE 1

40 rats were used for the tests described in this Example. Divided intofour groups of 10 rats each, the rats were given a subcutaneousinjection of 0.3 ml/100 g. body weight of the solutions containing thefollowing:

    ______________________________________                                        Group 1 (Control)                                                                            :    Saline                                                    Group 2 (Antihistamine)                                                                      :    63 micromoles/Kg. of                                                          mepyramine                                                Group 3 (H-2 Antagonist)                                                                     :    500 micromoles/Kg. of                                                         N-methyl-N'-[4(5)-imidazolyl)-                                                butyl]thiourea                                            Group 4 (Combination)                                                                        :    63 micromoles/Kg. of                                                          mepyramine plus 500 micromoles/                                               Kg. of N-methyl-N'-[-4(5)-                                                    imidazolyl)butyl]thiourea.                                ______________________________________                                    

30 minutes after this injection the plantar surface of a paw of each ratwas injected with 0.2 ml. of a solution containing 4 micrograms ofhistamine as irritant. The average change in paw colume (expressed as avolume-time integral over 4 hours) was assessed plethysmographically foreach group and is shown in Table 1. The values obtained for each ofgroups 2, 3 and 4 expressed as a percentage of that obtained for group1, are also shown.

                  TABLE 1                                                         ______________________________________                                                   Average Paw Volume                                                                             Percentage of                                     Group No.  Change           Group 1                                           ______________________________________                                        1          0.70 ± 0.14   100                                               2          0.08 ± 0.17   11                                                3          0.30 ± 0.19   43                                                4          -0.45 ± 0.14  0                                                 ______________________________________                                    

The negative figure obtained from group 4 is due to the fact that, notonly was no swelling caused by the histamine irritant but the paw volumeactually reduced due to the absorption during the time of the test ofthe originally injected vehicle.

EXAMPLES 2 to 6

The experiment described in Example 1 was repeated using, in place ofhistamine, the irritants as shown in table 2.

In each case it can be seen that the amount of swelling of the paw ofthe rats in group 4 is very considerably less than that in the case ofthe rats in group 2 or group 3.

EXAMPLE 7 to 22

The procedure of Example 2 (i.e. using 100 micrograms of 48/80 asirritant) was repeated using a two groups of 10 rats corresponding togroup 1 and 4 in Examples 1 to 6. Thus one group of 10 rats were given asubcutaneous injection of 0.3 ml/100 g. body weight of saline and asecond group of 10 rats was administered a subcutaneous injection of 0.3ml/100 g. body weight of a solution containing 88 micromoles/Kg. ofmepyramine and 500 micromoles/Kg. of an H-2 antagonist as shown in Table3. The average change in paw volume in the rats of the second groupexpressed, as in Example 1 to 6, as a percentage of the

                                      TABLE 2                                     __________________________________________________________________________    Example No                                                                             2          3          4          5         6                         __________________________________________________________________________    Irritant 48/80      5/HT       Yeast      Kaolin    Carageenin                Amount of                                                                     Irritant Used/                                                                         100 micrograms                                                                           25 micrograms                                                                            250 micrograms                                                                           50 micrograms                                                                           20 micrograms             Vol. Injected                                                                          in 0.2 ml. in 0.1 ml. in 0.2 ml. in 0.1 ml.                                                                              in 0.1                    __________________________________________________________________________                                                        ml.                                Av. Vol.   Av. Vol.   Av. Vol.   Av. Vol.  Av. Vol.                           Change                                                                              % age                                                                              Change                                                                              % age                                                                              Change                                                                              % age                                                                              Change                                                                              % age                                                                             Change                                                                              %                   __________________________________________________________________________                                                              age                 Group 1  3.10  100  2.35  100  2.55  100  1.65  100 1.85  100                          ± 0.20  ± 0.22  ± 0.15  ± 0.25 ± 0.28                 Group 2  2.70  87   1.80  76   1.65  65   0.95  58  1.45  78                           ± 0.35  ± 0.20  ± 0.15  ± 0.17 ± 0.20                 Group 3  2.80  90   1.50  64   1.70  67   1.26  76  1.85  100                          ± 0.25  ± 0.20  ± 0.20  ± 0.17 ± 0.28                 Group 4  0.90  29   0.15  6    0.80  31   0.65  39  0.85  46                           ± 0.20  ± 0.12  ± 0.15  ± 0.15 ± 0.19                 __________________________________________________________________________

                  TABLE 3                                                         ______________________________________                                        Example                                                                       No.      H - 2 Antagonist Used                                                ______________________________________                                        7      N-[4-(4-imidazolyl)butyl]thiourea                                      8      N-methyl-N'-[4-(2-thiazolyl)butyl]thiourea                             9      N-methyl N'-[4-(4-bromo-5-imidazolyl)butyl]-                                  thiourea                                                               10     N-methyl-N'-[5-(4-imidazolyl)pentyl]thiourea                           11     N-methyl-N'-[3-(4-imidazolyl)propyl]thiourea                           12     N-isopropyl-N'-[4-(4-imidazolyl)butyl]thiourea                         13     N-methyl-N'-[4-(3-(1,2,4)-triazolyl)butyl]-                                   thiourea                                                               14     N-methyl-N'-[2-((4-methyl-5-imidazolyl)-                                      methylthio)ethyl]thiourea                                              15     N-methyl-N'-[2-(4-imidazolylmethylthio) ethyl]-                               thiourea                                                               16     N-cyano-N'-methyl-N"-[2-((4-methyl-5-imidazolyl)-                             methylthio)ethyl]guanidine                                             17     N-methyl-N'-[3-(4-imidazolylmethylthio)-                                      propyl]thiourea                                                        18     N-methyl-N'-[2-((4-isopropyl-5-imidazolyl)-                                   methylthio) ethyl]thiourea.                                            19     S-(2-phenoxyethyl)-N-3-(4-imidazolyl)-propyl                                  isothiourea                                                            20     S-(p-chlorobenzyl)-N-[3-(4-imidazolyl) propyl]-                               isothiourea                                                            21     S-ethyl-N-[3-(4-imidazolyl)propyl]isothiourea                          22     4-(3-guanidinopropyl)-imidazole                                        ______________________________________                                    

change observed in the control group lay within the range of from 15% to70%.

EXAMPLE 23

The procedure of Examples 7 to 22 was repeated using, as H-2 antagonist500 micromoles/Kg. of the following compounds:

a. N,N'-dimethyl-S-[2-(4(5)-imidazolyl)ethyl]isothiourea

b. S-[4-(4(5)-imidazolyl)butyl]isothiourea

c. 5- (4(5)-imidazolyl)valeramidine

d. N-methyl-N'-[4-(2-pyridyl)butyl]thiourea

e. N-methyl-N'-[2-((3-pyridazinyl)methylthio)ethyl]-thiourea

f. N-methyl-N'-[2-((3-hydroxy-2-pyridyl)methylthio)-ethyl]thiourea

g.N-methyl-N'-[2-((5-(2-amino-1,3,4-thiadiazolyl)-methylthio)ethyl]thiourea.

h. N-methyl-N'-[3-(2-oxazolyl)thiopropyl]thiourea

i. N-methyl-N'-[2-(4-imidazolylmethoxy)ethyl]thiourea

j. N-methyl-N'-[3-(2-pyridylamino)propyl]thiourea

k. N-methyl-N'-[2-((4-methyl-5-imidazolyl)methylthio)-ethyl]urea

l. 2-[(4-imidazolyl)methylthio]ethylguanidine

m. N-(2-[(4-methyl-5-imidazolyl)methylthio]ethyl)-N'-nitroguanidine

n. N-methyl-N'-[2-(4-trifluoromethyl-5-imidazolyl)-methylthio)ethyl]thiourea

o. N-methyl-N'-[2-(2-pyrimidyl)methylthio)ethyl]thiourea

p. N-methyl-N'-[2-(2-pyrazinyl)methylthio)ethyl]thiourea

q. N-methyl-N'-[2-(4-bromo-3-isothiazolyl)methylthio)-ethyl]thiourea.

In each case the average swelling of the rat's paw in the second groupwas very much less than in the case of the control group.

EXAMPLES 24 and 25

The procedure of Examples 7 to 21 was repeated, the second group of 10rats being administered subcutaneously 0.3 ml/100 g. body weight of asolution containing 500 micromoles/Kg. ofN-methyl-N'-[4-(4(5)-imidazolyl)butyl] thiourea and an antihistamine asshown in Table 4. The table also shows the average paw volume changeexpressed as a percentage of the control group.

                  TABLE 4                                                         ______________________________________                                        Example               Amount of                                               No.    Antihistamine Used                                                                           Antihistamine % age                                     ______________________________________                                        24     Promethazine   88 micromoles/Kg.                                                                           0.6                                       25     Mebrophenhydramine                                                                           72 micromoles/Kg.                                                                           0.0                                       ______________________________________                                    

EXAMPLE 26

The procedure of Examples 24 and 25 was repeated using as antihistaminefrom 50 to 100 micromoles/Kg. of the following substances:diphenhydramine, chlorpheniramine, triprolidene, antazoline,bromodiphenhydramine, parabromdylamine, carbinoxamine, cyproheptadine,chlorcyclizine, dimethindene, diphenylpyraline, dimethothiazine,methdilazine, trimeprazine, mebhydroline, methapyrilene, phenindamine,pheniramine, phenyltoloxamine and pyrrobutamine. In each case theaverage swelling of rats paw in the second group was very much less thanin the case of the control group.

EXAMPLE 27

Four groups each of 7 guinea-pigs were injected subcutaneously withcompositions corresponding to those given to rats in groups 1 - 4 inexperiments 1 to 6. Thirty minutes later three 0.5 cm. diameter circleson the depilated skins of the guinea-pigs were irradiated for 1 minutewith a Hanovia U.V. lamp and the intensity of the resultant areas oferythema were scored after 2 and 5 hours.

The scoring system used was to assign 0, 1/2 or 1 to each irradiatedcircle according to the intensity of erythema; for each animal, fullydeveloped erythema in each circle would give a maximum score of 3 andthe maximum score for each group of 7 animals would be 21. Assessmentswere made by two investigators who scored the results independently on acompletely "blind" basis. Analysis of variance showed that there was nosignificant differences between observers and their scores have beenaveraged as shown in Table 5.

                  TABLE 5                                                         ______________________________________                                        Treatment      Hours                                                          ______________________________________                                                       2                5                                             Group 1        16               17                                            Group 2        6                15                                            Group 3        5                7                                             Group 4        1.5              4                                             ______________________________________                                        ANALYSIS OF VARIANCE                                                          F and p                                                                       Group 2        36.39        3.95                                                             0.001        N.S.                                              Group 3        47.76        64.43                                                            0.001        0.001                                             Group 4        7.5          0.22                                                             0.01         N.S.                                              ______________________________________                                    

EXAMPLE 28

To cats, anaesthetised with an intravenously administered dose of 100mg/Kg. of chloralose, was intravenously given doses of histamine in therange of 0.01 to 0.10 micromoles/Kg. of histamine. The resultantvasodilation and hypotension was not affected by an intravenous dose of35 micromoles/Kg. of mepyramine but a subsequent intravenous infusion ofN-methyl-N'-[4-(4(5)-imidazolyl)-butyl] thiourea at a rate of 3micromoles/Kg./minute over 30 minutes completely abolished thehypotension.

EXAMPLE 29

The experiment of Example 28 was repeated in dogs which had beenanaesthetised with an intravenously administered dose of 30 mg./Kg. ofnembutal. The hypotension was again abolished.

In the case of both Example 28 and 29, the abolition ofhistamine-induced hypotension could be equally well achieved by a singleintravenous dose of a composition comprising 35 micromoles/Kg. ofmepyramine and 90 micromoles/Kg. ofN-methyl-N'-[4-(4(5)-imidazolyl)butyl]-thiourea.

EXAMPLE 30

The experiments of Examples 28 and 29 were repeated using, as H-2antagonist 9 micromoles/Kg. ofN-methyl-N'-[2-((4-methyl-5-imidazolyl)methylthio)ethyl]thioureaadministered intravenously either in a composition also comprising 35micromoles/Kg. of mepyramine or subsequently to the mepyramine as aninfusion over 30 minutes.

EXAMPLE 31

The experiments of Examples 28 and 29 were repeated using, asantihistamine (a) 18 micromoles/Kg. of promethazine and (b) 14micromoles/Kg. of mebrophenhydramine. In each case the hypotension wasabolished.

EXAMPLE 32

To rabbits, anaesthetised with an intraperitoneally administered mixtureof 700 mg/Kg. of urethane and 40 mg/Kg. of pentobarbitone, histamine inthe dose range 0.0625 to 0.50 micromoles/Kg. was given intravenously andproduced pressor responses. An intravenous dose of 3.5 micromoles/Kg. ofmepyramine reversed this pressor response to a depressor responsewhereas an intravenous dose of 1 micromole/Kg./minute ofN-methyl-N'-[4-(4(5)-imidazolyl)butyl]thiourea over 30 minutespotentiated the histamine-induced pressor response. However, theintravenous administration of a solution comprising both 3.5micromoles/Kg. of mepyramine and 30 micromoles/Kg. ofN-methyl-N'-[4(4(5)-imidazolyl)-butyl]thiourea completely abolished thehistamine-induced pressor response.

EXAMPLE 33

When the experiments of Examples 28, 29 or 32 are repeated using, as H-2antagonist any of the substances set out in Examples 7 to 14 and 16 to23 in conjunction with mepyramine as antihistamine, thehistamine-induced cardiovascular effects are abolished in each case.

EXAMPLE 34

When the experiments of Examples 28, 29 or 32 are repeated usingN-methyl-N'-[4-(4(5)-imidazolyl)butyl]thiourea as H-2 antagonist and anyof the substances listed in Example 26 as anti-histamine, thehistamine-induced cardiovascular effects are abolished in each case.

EXAMPLE 35

A group of seven rats were anaesthetised by intraperitoneal injection of60 mg./Kg. of pentobarbitone sodium, under which conditions their bloodpressure was of the order of 110 mm.Hg. Intravenous infusion of salineat a rate of 1 ml/hour was commenced and, after 30 minutes anintravenous injection of 5 mg./Kg. of lipopolysaccharide B derived fromS. enteritidis was given. Within a short period (about 10-15 minutes)the blood pressure had fallen to an average minimum level of 23 mm. Hg.A second group of seven rats similarly treated but in this case theintravenous infusion was of a composition according to the presentinvention comprising a solution of promethazine andN-methyl-N'-[2-((5-methyl-4-imidazolyl)methylthio)-ethyl]thiourea in amolar weight ratio of 1:10. This solution was administered at a ratesuch that, over the 30 minutes prior to the intravenous injection of theendotoxin, 60 micromoles/Kg. rat body weight of mepyramine and 600micromoles/Kg. rat body weight ofN-methyl-N'-[2-((5-methyl-4-imidazolyl)methylthio)ethyl]-thiourea hadbeen given. The average minimum blood pressure which again was measuredafter 10-15 minutes from the injection of the endotoxin was in this case37 mm.Hg.

EXAMPLE 36

When the experiment of Example 35 is repeated using as the compositionof our invention any one of the H-2 antagonist substances set out inExamples 1,7-13 and 15 to 23 in conjunction with any one of theantihistamine listed in Example 26, mapyramine or mebrophenhydramine,similar results are obtained.

                  EXAMPLE 37                                                      ______________________________________                                         Ingredients             Amounts                                              ______________________________________                                        N-methyl-N'-[4-(4(5)-imidazolyl)-                                             butyl]thiourea          250 mg.                                               mepyramine              120 mg.                                               sucrose                 100 mg.                                               starch                  20 mg.                                                talc                    7 mg.                                                 stearic acid            3 mg.                                                 ______________________________________                                    

The ingredients are screened, mixed and filled into a hard gelatincapsule.

                  EXAMPLE 38                                                      ______________________________________                                         Ingredients             Amounts                                              ______________________________________                                        N-methyl-N'-[2-((5 methyl-4-                                                  imidazolyl)methylthio)ethyl]-                                                 thiourea                200 mg.                                               mebrophenhydramine      150 mg.                                               lactose                 150 mg.                                               ______________________________________                                    

The ingredients are screened, mixed and filled into a hard gelatinecapsule.

                  EXAMPLE 39                                                      ______________________________________                                         Ingredients             Amounts                                              ______________________________________                                        N-methyl-N'-[4-(4(5)-imidazolyl)-                                             butyl]thiourea          100 mg.                                               Promethazine            50 mg.                                                ______________________________________                                    

The ingredients are dissolved in distilled water and packaged intosealed ampoules.

The compositions prepared as in Examples 37 to 39 are administered to asubject within the dose ranges given hereabove to produceanti-inflammatory activity.

EXAMPLE 40 Preparation of S-[2-(4(5)-imidazolyl)ethyl]isothioureadihydrobromide

A solution of 4(5)-(2-hydroxyethyl)imidazole (6.0 g.) and thiourea (4.1g.) in 48% aqueous hydrobromic acid (37 ml.) is heated under reflux for17 hours. Following evaporation to dryness, the solid residue isrecrystallized from isopropyl alcohol-ethanol-ether, yieldingS-[2-(4(5)-imidazolyl)ethyl]-isothiourea dihydrobromide, m.p. 208°-212°C. Recrystallization from the same solvents yields pure product, m.p.210°-212° C.

EXAMPLE 41 Preparation ofN,N'-dimethyl-S-[2-(4(5)-imidazolyl)ethyl]-isothiourea dihydrobromide

A mixture of 4(5)-(2-hydroxyethyl)imidazole (2.24 g.),N,N'-dimethylthiourea (2.04 g.) and 48% aqueous hydrobromic acid (12ml.) is caused to react in a manner similar to that described in Example40. The pure product m.p. 203°-204° C., is obtained by recrystallizationfrom absolute alcohol.

EXAMPLE 42 Preparation of S-[4-(4(5)-imidazolyl)butyl]isothioureadihydrobromide

4-[4(5)-Imidazolyl]butyric acid hydrochloride (72.0 g.) is esterifiedusing a solution of gaseous hydrogen chloride in ethanol (14.5%). Thesolution is heated under reflux for 18 hours in the presence of amolecular sieve contained in a Soxhlet apparatus. Concentration affordsthe ethyl ester hydrochloride (78.2 g.) which is converted into the baseby dissolving in absolute alcohol (200 mg.) and neutralizing with asolution prepared from sodium (7.93 g.) in alcohol (250 ml.). Followingremoval of inorganic material the crude ester base (54.7 g.) is isolatedand used without further purification. This ester is dissolved inanhydrous tetrahydrofuran (700 ml.) and added slowly to a stirredsuspension of lithium aluminium hydride (46.6 g.) in anhydroustetrahydrofuran (220 ml.). Stirring is continued at room temperature for17 hours, whereupon water (84 ml.) is slowly added, followed by theapplication of moderate heat for 15 minutes. The solid present isremoved by filtration and extracted three times with hottetrahydrofuran. The combined extracts are evaporated, affording4(5)-(4-hydroxybutyl)imidazole (23 g.), a sample of which is convertedinto an oxalate salt, m.p. 104°-106° C.

A mixture of 4(5)-(4-hydroxybutyl)imidazole (2.24 g.), thiourea (1.22g.) and 48% aqueous hydrobromic acid (10 ml.) is caused to react in amanner similar to that described in Example 40. The initial productobtained (m.p. 110°-115° C.) is recrystallized frommethanol-nitromethane-ethyl acetate affordingS-[4-(4(5)-imidazolyl)butyl]isothiourea dihydrobromide in three crops:

1.1 g. m.p. 113°-114° C.; 0.4 g. m.p. 109°-113° C.; 0.6 g. m.p.110°-112° C.

EXAMPLE 43 Preparation ofS-ethyl-N-[3-(4(5)-imidazolyl)propyl]isothiourea dihydriodide andsulphate

Ethyl iodide (12.5 g.) is added to a solution ofN-[3-(4(5)-imidazolyl)propyl]thiourea hydriodide (23.0 g.) in absoluteethanol (250 ml.) containing water (2 ml.). The resultant solution isheated under reflux for four hours and concentrated under reducedpressure. Recrystallization of the residue from ethanol-ether yieldsS-ethyl-N-[3-(4(5)-imidazolyl)-propyl]isothiourea dihydriodide, m.p.113°-114° C.

A solution of S-ethyl-N-[3-(4(5)-imidazolyl)propyl]-isothioureadihydriodide (20 g.) in water is passed down an ion-exchange column (SO₄⁻ ⁻ form, 250 ml.). Following elution with water, the eluate isconcentrated under reduced pressure. Recrystallization of the residuefrom water-isopropyl alcohol yieldsS-ethyl-N-[3-(4(5)-imidazolyl)propyl]isothiouronium sulphate, m.p.184°-186° C.

EXAMPLE 44 Preparation ofS-(p-chlorobenzyl)-N-[3-(4(5)-imidazolyl)propyl]-isothioureadihydrochloride

The solution obtained from the addition of p-chlorobenzyl chloride (1.3g.) to N-[3-(4(5)-imidazolyl)propyl]thiourea (1.5 g.) in 2N hydrochloricacid (25 ml.) containing acetone (15 ml.) is heated under reflux for 2.5hours. Concentration followed by recrystallization fromethanol-isopropyl alcohol affordsS-(p-chlorobenzyl)-N-[3-(4(5)-imidazolyl)propyl]-isothioureadihydrochloride, m.p. 217°-219° C.

EXAMPLE 45 Preparation ofS-(2-phenoxyethyl)-N-[3-(4(5)-imidazolyl)propyl]-isothioureadihydrobromide

The solution obtained from the addition of 2-phenoxyethyl bromide (2.0g.) to N-[3-(4(5)-imidazolyl)propyl]-thiourea hydrobromide (2.6.) inabsolute ethanol (30 ml.) containing water (1 ml.) is heated underreflux for 48 hours. Concentration followed by recrystallization fromisopropyl alcohol-ether affordsS-(2-phenoxyethyl)-N-[3-(4(5)-imidazolyl)propyl]isothioureadihydrobromide, m.p. 153°-156° C.

EXAMPLE 46 Preparation of 3-(4(5)-imidazolyl)propylguanidine sulphate

Pure 4(5)-(3-aminopropyl)imidazole (10.5 g) is added to a solution ofS-methylthiouronium sulphate (11.8 g) in water (125 ml). The resultantsolution is refluxed for four hours, cooled and the acidified with theminimum quantity of sulphuric acid. Following concentration to lowvolume, ethanol is added which results in the separation of a colourlesssolid. This is filtered off, and twice recrystallized fromwater-methanol giving pure 3-(4(5)-imidazolyl)propylguanidine sulphate,m.p. 288°-290° C.

EXAMPLE 47 Preparation of N-[3-(4(5)-imidazolyl)propyl]acetamidinedihydrochloride

4(5)-(2-Chloroethyl)imidazole hydrochloride (200 g.) is dissolved indimethylformamide (600 ml.) and the solution treated with charcoal andfiltered. The filtrate is added gradually to a stirred suspension ofsodium cyanide (176 g.) in dimethylformamide (2.25 l.) maintained at130°-135° C. The addition requires 35 minutes and after this time thetemperature is maintained at 135° C. for five minutes. After cooling inan ice bath to 10° C., suspended solid is removed by filtration andwashed with dimethylformamide. The filtrate is concentrated underreduced pressure and final traces of dimethylformamide are removed withp-xylene (2×200 ml). The dry residue is dissolved in distilled water(500 ml.) and charged into a one liter extractor (volume includingwashings now 750 ml.) and extracted continuously with isopropyl acetate.The extracts are dried over magnesium sulphate, treated with charcoaland concentrated to low bulk. Cooling affords4(5)-(2-cyanoethyl)imidazole, m.p. 71°-74° C.

Alternative conditions for the synthesis of 4(5)-(2-cyanoethyl)imidazoleare as follows: a solution of 4(5)-(2-chloroethyl)imidazolehydrochloride (136 g.) in water (500 ml.) is added, with stirring to asolution of sodium cyanide (420 g.) in water (1.65 l.). The resultantmixture is heated at 60°-65° C. for 20 hours. After cooling, thesolution is treated with charcoal, filtered and concentrated underreduced pressure. The dry residue is extracted with hot ethyl acetate(5. l.) and the extracts are treated with charcoal and concentratedunder reduced pressure, affording 4(5)-(2-cyanoethyl)-imidazole, m.p.70°-71° C. A pure sample of the base, m.p. 71°-73° C., is obtained byrecrystallization from isopropyl acetate. A sample of the hydrochloride,m.p. 118°-120° C., is obtained by acidification with dry hydrogenchloride in ether.

A solution of 4(5)-(2-cyanoethyl)imidazole (61 g.) in absolute alcohol(600 ml.) is saturated with gaseous ammonia at -20° C. The resultantsolution is hydrogenated over Raney nickel catalyst (approximately 4 g.)at 100 atmospheres pressure for four hours at a temperature of 135°-145°C. After cooling, filtration and treatment with charcoal, the solutionis concentrated under reduced pressure, affording4(5)-3-aminopropylimidazole as a low melting solid. For purification,the amine (61 g.) is dissolved in a solution of sodium bicarbonate (82g.) in water (1.6 l.) and N-carbethoxyphthalimide (122 g.) added over0.5 hours. After stirring for 1.5 hours, the solid is collected, washedwith water and dried. Recrystallization from aqueous ethanol yields4(5)-(3-phthalimidopropyl)imidazole. A pure sample obtained by furtherrecrystallization from aqueous ethanol has m.p. 160°-162° C.

Hydrolysis with 5N hydrochloric acid for 16 hours followed by removal ofphthalic acid yields 4(5)-3-aminopropyl-imidazole dihydrochloride, m.p.156°-158° C. (from ethanol-ether). Treatment with sodium ethoxide inethanol yields pure 4(5)-(3-aminopropyl)imidazole.

Ethyl acetimidate hydrochloride (3.95 g.) is added rapidly to a mixtureof di-n-butyl ether (25 ml.) and a solution of potassium carbonate (4.4g.) in water (15 ml.). After shaking briefly, the organic layer isseparated, dried over sodium sulphate and filtered. A solution of4(5)-(3-aminopropyl)imidazole (2.0 g.) in dry ethanol (25 ml.) is addedto the filtrate and the resultant solution is allowed to stand at roomtemperature for seven days. The solution is then filtered, concentratedand acidified with ethanolic hydrogen chloride to give a hygroscopicsolid. Recrystallization from ethanol-ether with filtration in a dryatmosphere affords N-[3-(4(5)-imidazolyl)propyl]acetamidinedihydrochloride, m.p. 122°-128° C.

EXAMPLE 48 Preparation of 5-(4(5)-imidazolyl)valeramidinedihydrochloride

4-[4(5)-imidazolyl]butyric acid hydrochloride (72.0 g.) is esterfiedusing a solution of gaseous hydrogen chloride in ethanol (14.5%). Thesolution is heated under reflux for 18 hours in the presence of amolecular sieve contained in a Soxhlet apparatus. Concentration affordsthe ethyl ester hydrochloride (78.2 g) which is converted into the baseby dissolving in absolute alcohol (200 ml) and neutralizing with asolution prepared from sodium (7.93 g) in alcohol (250 ml). Followingremoval of inorganic material the crude ester base (54.7 g.) is isolatedand used without further purification.

This ester is dissolved in anhydrous tetrahydrofuran (700 ml) and addedslowly to a stirred suspension of lithium aluminium hydride (46.6 g.) inanhydrous tetrahydrofuran (220 ml.). Stirring is continued at roomtemperature for 17 hours whereupon water (84 ml) is slowly added,followed by the application of moderate heat for 15 minutes. The solidpresent is removed by filtration and extracted three times with hottetrahydrofuran. The combined extracts are evaporated to an oil (23 g) asample of which is converted into an oxalate salt, m.p. 104°-106° C. forcharacterisation.

The foregoing 4(5)-(4-hydroxybutyl)imidazole (10 g) is added slowly tothionyl chloride (20 ml) with stirring. The resultant solution is heatedon the steam bath for ten minutes and evaporated to an oil which isre-evaporated with benzene to remove last traces of thionyl chloride.The residual oil is dissolved in alcohol, treated with charcoal,concentrated and diluted with ether. Cooling affords4(5)-(4-chlorobutyl)imidazole hydrochloride as a stickly solid (12 g).Without further purification, the chloro compound (10.0 g) is dissolvedin anhydrous dimethylformamide (43 ml) and slowly added to a dispersionof sodium cyanide (8.3 g) in anhydrous dimethylformamide (330 ml) at110° C., with stirring. After addition, the mixture is maintained at110° C. for 15 minutes and then concentrated under reduced pressure. Theresidue is extracted with ethyl acetate and the extracts are treatedwith charcoal and evaporated to an oil. Cooling and agitation of the oilwith dry ether affords a crystalline solid (2.8 g.) which is collected.Recrystallization from ethyl acetate yields4(5)-(4-cyanobutyl)imidazole, m.p. 97°-99° C. The nitrile is obtainedanalytically pure by chromatographing on a column of silica gel andeluting with ethanol-ethylacetate.

The nitrile is converted into its hydrochloride salt (2.22 g) anddissolved in anhydrous methanol (5 ml). The solution is cooled andstirred during the slow addition of a saturated methanolic solution ofhydrogen chloride.

After addition the solution is stirred at 0° C. for three hours anddiluted with ether. The imino-ether hydrochloride separates as an oilwhich is washed twice with cold ether and dissolved in absolute alcohol(5 ml.). An ice cold solution prepared from anhydrous ammonia (2.1 g)and ethanol (15 ml) is added rapidly with external cooling. After onehour at 0° C. the mixture is allowed to attain room temperature.Ammonium chloride is filtered off and the filtrate is evaporated to anoil. A slight excess of ethanolic hydrogen chloride is added and thesolution is again evaporated. Trituration of the residue with a littleabsolute alcohol followed by recrystallization from ethanol-etheraffords pure 5-(4(5)-imidazolyl)valeramidine dihydrochloride, m.p.221°-222° C.

EXAMPLE 49 Preparation of N-methyl-N'-[3-(4(5)-imidazolyl)propyl]thiourea

Methyl isothiocyanate (2.92 g) is added to a solution of4(5)-(3-aminopropyl)imidazole (5.0 g.) in chloroform (100 ml) anddimethylformamide (10 ml). The resultant solution is heated under refluxfor 2.5 hours and evaporated to dryness. The residue is treated withethanolic hydrogen chloride which affords a hygroscopic hydrochloride.This is recrystallized from ethanol-ether and converted to the base withaqueous potassium carbonate. Evaporation followed by extraction withethanol yields the crude base which after recrystallisation from wateryields pure N-methyl-N'-(3-(4(5)-imidazolyl)propyl)thiourea, m.p.135°-137° C.

EXAMPLE 50 Preparation of N-[4-(4(5)-imidazolyl)butyl]thiourea

N-Benzoyl-N'-[4-(4(5)-imidazolyl)butyl]thiourea hydrothiocyanate (1.5 g)is added with stirring to 10% aqueous potassium hydroxide (30 ml) at65°-70° C. After 15 minutes the mixture is cooled, acidified with dilutehydrochloric acid, and after two hours at 5° C. is filtered from thebenzoic acid which precipitates. The filtrate is basified with anhydrouspotassium carbonate and concentrated to dryness under reduced pressureto yield a residue which is extracted with hot ethanol. The extract isconcentrated to 5 ml and cooled to yield colourless crystals. Thelatter, after being crystallized from water (9 ml) furnishesN-[4-(4(5)imidazolyl)butyl]thiourea, m.p. 166°-167° C.

EXAMPLE 51 Preparation of N-methyl-N'-[4-(4(5)-imidazolyl)butyl]thiourea

4(5)-(4-Aminobutyl)imidazole (15.0 g. containing approximately 12% w/wethanol) is dissolved in warm acetonitrile (100 ml). The solution isfiltered, methyl isothiocyanate (7.3 g) is added and the resultantsolution is heated under reflux for 1.5 hours. Following concentration,the residual oil is triturated several times with warm isopropyl acetatewhich affords the thiourea in crystalline form.

Recrystallization from acetonitrile-isopropyl acetate yieldsN-methyl-N'-[4-(4(5)-imidazolyl)butyl]thiourea. After furtherrecrystallization from acetonitrile, followed by recrystallization fromwater, the product melts at 127°-128° C.

EXAMPLE 52 Preparation of N-isopropyl-N'-(4-(4(5)-imidazolyl)butyl)thiourea

4(5)-(4-aminobutyl)imidazole (1.3 g) is caused to react with isopropylisothiocyanate (1.0 g) by a procedure similar to that described inExample 51. Recrystallization from aqueous isopropyl alcohol affordsN-isopropyl-N'-(4-(4(5)-imidazolyl)butyl)thiourea m.p. 138°-139° C.

EXAMPLE 53 Preparation ofN-methyl-N'-[5-(4(5)-imidazolyl)pentyl]thiourea.

i. A mixture of 1-bromo-7-phthalimidoheptan-2-one (obtainable from8-aminocaproic acid) (60.0 g) and formamide (360 ml) is heated at180°-185° C for two hours. Following removal of excess formamide bydistillation under reduced pressure, the residue is hydrolysed byheating under reflux with 6N hydrochloric acid (1.8 l.) for 18 hours.After cooling to 0° C and filtering to remove phthalic acid, thefiltrate is concentrated under reduced pressure and the residueextracted with hot enthanol and again concentrated. The residual aminehydrochloride is converted to the free base by passage down anion-exchange resin (OH--) and elution with methanol. The base obtainedis converted into the picrate with picric acid (82.5 g) in water. Thepicrate is recrystallized several times from water affording4(5)-(5-amino-pentyl)imidazole dipicrate, m.p. 209°-211° C. Meltingpoint of an analytically pure sample (from nitromethane) is 210°-211° C.

The picrate is treated with hydrochloric acid in the usual way, yieldingthe amine dihydrochloride which is finally converted to4(5)-(5-aminopentyl)imidazole, m.p. 45°-48° C., by passage downion-exchange resin (OH--). ii. A solution of methyl isothiocyanate (2.92g) and 4(5)-(5-aminopentyl)imidazole (6.13 g) in acetonitrile (40 ml) isheated under reflux for three hours. Cooling, followed byrecrystallization of the product from acetonitrile affordsN-methyl-N'-[5-(4(5)-imidazolyl)pentyl]thiourea, m.p. 108°-109° C.

EXAMPLE 54 Preparation of N-methyl-N'-(4-(5-bromo-4-imidazolyl)butyl)thiourea

i. To a stirred mixture of (4(5)-(4-aminobutyl)imidazole (15.8 g,containing 8% weight/weight ethanol) in concentrated sulphuric acid (250ml) is added silver sulphate (31.2 g). Light is excluded from thereaction mixture and bromine (10.75 ml) is added, followed by sulphuricacid washings (25 ml). The reaction mixture is stirred in the dark for2-5 days, filtered and the precipitate washed with sulphuric acid (50ml). The combined filtrates are added to water (1L.) and neutralised topH 6-7 with sodium carbonate with cooling. Following filtration, thefiltrate is concentrated under reduced pressure. The residue isconverted to the hydrochloride using hydrogen chloride in isopropylalcohol. The hydrochloride is passed down Amberlite ion-exchange resinIRA 401 (SO₄ ⁻ ⁻) and eluted with water. The eluate is concentratedunder reduced pressure and the residue extracted with methanol anddiluted with ethanol yielding 5-bromo-4-aminobutylimidazole sulphate(15.8 g). Recrystallization from water-methanol-ethanol affords theanalytically pure product (11.2 g), m.p. 92°-95° C. ii. A solution of5-bromo-4-aminobutylimidazole (2.39 g) prepared from the hydrochlorideand potassium carbonate) and methyl isothiocyanate (0.73 g) in ethanol(10 ml) is heated under reflux for 2 hours. Concentration followed byrecrystallization of the residue twice from ethanolether affordsN-methyl-N'-(4-(5-bromo-4-imidazolyl)butyl) thiourea m.p. 153°-155° C.

EXAMPLE 55 Preparation of N-methyl-N'-(4-(3-(1,2,4-triazolyl)butyl)thiourea

i. 5-Phthalimidovaleroyl chloride (90.0 g) is added portionwise to asuspension of thiosemicarbazide (34.0 g) in anhydrous pyridine (220 ml)at 0°-5° C. After addition the mixture is kept at 0° C for 1 hour andset aside overnight at room temperature. Following addition to water (2l.) the white solid is collected and washed with 50% aqueous acetic acidand then water. Recrystallization from nitromethane affords1-(5-(phthalimidovaleroyl) thiosemicarbazide (69 g), m.p. 196° C.

ii. 1-(5-(Phthalimidovaleroyl))thiosemicarbazide (69 g) dissolved in asolution prepared from sodium (6.25 g) in ethanol (860 ml) is heatedunder reflux for 16 hours. Concentration to low bulk, followed by theaddition of ice-water affords a white crystalline solid, which iscollected and washed successively with water, ethanol and ether to give3-(4-phthalimidobutyl)-1,2,4-triazoline-5-thione (33 g), m.p. 223°-225°C.

iii. The triazolinethione (30.5 g) is dissolved in ethanol (360 ml) andheated under reflux with stirring for 2 hours in the presence of RaneyNickel (90 g). Filtration, followed by concentration and the addition ofwater affords 3-(4-phthalimidobutyl)-1,2,4-triazole (13.3 g) m.p.169°-171° C. A sample recrystallised from water has m.p. 171°-172° C.

iv. The phthalimido derivative (13.0 g.) is hydrolysed with 5Nhydrochloric acid for 8 hours under reflux. Following cooling andremoval of phthalic acid, the filtrate is concentrated. The solidresidue is triturated with ethanol-ether (1:1) and filtered to afford3-(4-aminobutyl)-1,2,4-triazole dihydrochloride (10.0 g), m.p. 171°-172°C.

v. The amine hydrochloride (5.0 g) is converted into its free base withaqueous potassium carbonate by concentration followed by extraction withethanol-ether (3:1). The base is dissolved in ethanol and caused toreact with methylisothiocyanate (1.87 g) in ethanol. The productobtained is recrystallized from water followed by ethanol-ether toafford N-methyl-N'-(4-(3-(1,2,4-triazolyl)butyl)thiourea (3.15 g), m.p.133°-134° C.

EXAMPLE 56 Preparation of N-methyl-N'-(4-(2-pyridyl)butyl)thiourea

i. 2-(3-cyanopropyl)pyridine (14.6 g) in dry ether (100 ml) is addeddropwise to a stirred suspension of lithium aluminium hydride (9.5 g) indry ether (300 ml). The mixture is heated under reflux for 3 hours,cooled and treated successively with water, aqueous sodium hydroxide andwater. Extraction with chloroform, followed by fractionation affords2-(4-aminobutyl)pyridine (6.7 g), b.p. 100°-101° C/1.0 mm.

ii. The reaction of 2-(4-aminobutyl)pyridine (3.0 g) and methylisothiocyanate (1.6 g) in ethanol (25 ml) for 0.5 hours followed bychromatography of the product on silica and elution with ethyl acetateaffords N-methyl-N'-(4-(2-pyridyl)butyl)thiourea (3.0 g) as a colourlessoil.

EXAMPLE 57 Preparation of N-methyl-N'-(4-(2-thiazolyl)butyl)thiourea

i. Liquid ammonia (20 g) and 4-phthalimidovaleronitrile (67 g) is addedto a cooled solution of hydrogen sulphide (50 g) in methyl alcohol (500ml). The sealed reaction vessel is the heated at 40° for 3 days withstirring. Concentration followed by recrystallization from isopropylacetate yields 4-phthalimidothiovaleramide, m.p. 143°-146° C.

ii. A mixture of the thioamide (11.0 g) and bromacetal (8.3 g) is heatedfor 1 hour on the steam-bath. Following filtration and washing withwater, the crude product is dissolved in hydrochloric acid andprecipatated by the addition of saturated sodium acetate.Recrystallization from isopropyl alcohol-water finally yields2-(4-phthalimidobutyl)thiazole (5.22 g) m.p. 86°-88° C.

iii. 2-(4-Phthalimidobutyl)thiazole (5.0 g) is hydrolysed withhydrochloric acid in the usual way. The amine hydrochloride obtained isbasified with potassium carbonate and extracted with ether-ethanol (3:1)to give 2-(4-amino-butyl)thiazole as a colourless oil. The reaction ofthe amine (2.0 g) and methyl isothiocyanate (0.98 g) in ethanol (10 ml)for 1 hour, followed by chromatography of the product on silica gel withethyl acetate as eluent gives N-methyl-N'-(4-(2-thiazolyl)butyl)thiourea (2.5 g) as a colourless oil. Formation of the hydrobromide saltyields a crystalline solid, m.p. 130°-132° C.

EXAMPLE 58 N-Methyl-N'-[2-((4-imidazolyl)methylthio)ethyl]thiourea

i. (a) A solution of 4(5)-hydroxymethylimidazole hydrochloride (67 g)and cysteamine hydrochloride (56.8 g) in aqueous hydrobromic acid (1liter, 48%) was heated under reflux overnight. After cooling, thesolution was evaporated to dryness and the residual solid washed withethanol/ether to give 4(5)-[(2-aminoethyl)thiomethyl]imidazoledihydrobromide (156 g.), m.p. 178°-179°.

b. Phthalimidoethanethiol (2 g.) was added portionwise with stirring toa solution of sodium ethoxide (prepared from 0.23 g. of sodium) inethanol (20 ml.) at 0° under a nitrogen atmosphere. After stirring at 0°for a further 21/2 hours, the resulting yellow solution was cooled withan ice-salt bath and a solution of 4(5)-chloromethylimidazolehydrochloride (0.76 g.) in ethanol (5 ml.) was added dropwise over 10minutes. After addition the mixture was stirred at room temperatureovernight, then acidified with ethanolic hydrogen chloride andevaporated to dryness. Addition of water precipitated unreactedphthalimidoethanethiol (0.6 g.) which was removed by filtration. Thefiltrate was concentrated and basified with aqueous sodium bicarbonatesolution to furnish a white precipitate which, on recrystallisation fromaqueous ethanol, gave 4(5)-[(2-phthalimidoethyl)thiomethyl]imidazole(0.75 g.) m.p. 136°-137°. A stirred mixture of this phthalimidoderivative (0.62 g.) in aqueous hydrobromic acid (40 ml. 18%) was heatedunder reflux overnight. After cooling to 0°, the resulting clearsolution was filtered and the filtrate evaporated to dryness.Recrystallisation of the residue from ethanol gave4(5)-[(2-aminoethyl)thiomethyl]imidazole dihydrobromide (0.52 g.), m.p.178°-179°.

c. A suspension of cysteamine hydrochloride (118.8 g.) in ethanol (200ml., dried over molecular sieves) was added portionwise at 0° to asolution of sodium ethoxide (prepared from 48 g. of sodium) in ethanol(1 liter) under a nitrogen atmosphere. After stirring at 0°, for afurther 2 hours, a solution of 4(5)-chloromethylimidazole hydrochloride(80 g.) in ethanol (400 ml.) was added dropwise over 45 minutes whilethe temperature was maintained at -1° ± 2°. After addition, the mixturewas stirred at room temperature overnight, filtered and the filtrateacidified with concentrated hydrochloric acid. The solution was thenevaporated to dryness, the residue dissolved in ethanol (1 liter) and asolution of excess picric acid in hot ethanol added. The resulting crudepicrate was dissolved in water (2.7 liters) and, after decantation froman insoluble oil, the solution was left to cool to give4(5)-((2-aminoethyl)thiomethyl) imidazole dipicrate, m.p. 194°-195°.Treatment of this picrate with aqueous hydrobromic acid followed byextraction with toluene gave the dihydrobromide, m.p. 178°-179°, afterevaporation to dryness and recrystallisation of the crude residue fromethanol.

ii. A solution of 4(5)-((2-aminoethyl)thiomethyl) imidazoledihydrobromide (10 g.) in water (25 ml.) was basified to pH 11 by theaddition of a solution of potassium carbonate (8.7 g.) in water (25ml.). The resulting solution was evaporated to dryness, extracted withisopropyl alcohol and the final traces of water removed by azeotropingwith isopropyl alcohol. The residual amine was extracted from theinorganic material with isopropyl alcohol, the extracts concentrated toabout 70 ml. and a solution of methyl isothiocyanate (2.3 g.) inisopropyl alcohol (5 ml.) added. The reaction mixture was then heatedunder reflux for 11/2 hours and, after cooling, evaporated to dryness.The residual oil was dissolved in acetone, the solution filtered toremove traces of inorganic material, and the filtrate concentrated togive N-methyl-N'-(2-(4-imidazolylmethylthio)ethyl)thiourea (4.1. g.),m.p. 96°-98°. A sample, recrystallised from acetone, had m.p. 98°-99°.

EXAMPLE 59N-Methyl-N'-[2-((5-methyl-4-imidazolyl)methylthio)ethyl]thiourea

i. (a) A solution of 4-hydroxymethyl-5-methylimidazole hydrochloride(30.0 g) and cysteamine hydrochloride (23.0 g.) in acetic acid (200 ml.)was heated under reflux for 10 hours. Following cooling to 15°-20°, thesolid which crystallised was collected and washed with isopropyl alcoholto give 4-methyl-5-[(2-aminoethyl)thiomethyl]-imidazole dihydrochloride(45.5 g), m.p. 189°-192°.

b. A solution of 4-hydroxymethyl-5-methylimidazole hydrochloride (30.0g.) and cysteamine hydrochloride (23.0 g) in concentrated aqueoushydrochoric acid (450 ml.) was heated under reflux for 17 hours.Concentration followed by re-evaporation with water afforded a residuewhich was dissolved in isopropyl alcohol, concentrated to low bulk andcooled to afford 4-methyl-5-[(2-aminoethyl)thiomethyl]imidazoledihydrochloride (40.6 g.), m.p. 185°-191°.

c. A mixture of 4-hydroxymethyl-5-methylimidazole hydrochloride (15.0g.), cysteamine hydrochloride (11.5 g.) and a solution of hydrogenbromide in acetic acid (48%, 225 ml.) was heated under reflux for 7hours. Cooling afforded 4-methyl-5-[(2-aminoethyl)thiomethyl]imidazoledihydrobromide (21.6 g.), m.p. 208°-211°.

ii. Potassium carbonate (7.75 g.) was added to a solution of4-methyl-5-[(2-aminoethyl)thiomethyl]imidazole

dihydrochloride (14.6 g.) in water (120 ml.). The solution was stirredat room temperature for 15 minutes and methyl isothiocyanate (5.15 g.)was added. After heating under reflux for 30 minutes, the solution wasslowly cooled to 5°.

The product (13.1 g) was collected and re-crystallised from water togive N-methyl-N'-[2-((5-methyl-4-imidazolyl) methylthio)ethyl]thiourea,m.p. 150°-152°.

EXAMPLE 60 Preparation ofN-methyl-N'-[2-(5-isopropyl-4-imidazolyl)-methylthio)ethyl]thiourea.

i. A solution of sodium nitrite (43.8 g.) in water (92 ml.) was addeddropwise, with stirring, to a solution of ethyl isobutyrylacetate (100.3g.) in acetic acid (80 ml.) at 0°. After stirring at 0° for 30 minutesthen at room temperature for 3 hours, water (100 ml.) was added and themixture extracted with ether. The extracts were washed with water,saturated sodium bicarbonate solution and water. After drying (CaSO4),the solution was evaporated to give ethyl2-oximino-4-methyl-3-oxopentanoate (112 g.) as a crude oil.

A solution of this oximinoketone (219 g.) in ethanol (280 ml.) was addedto a suspension of pre-reduced palladised charcoal (10 g., 10%) inethanol (1 lit.) and saturated ethanolic hydrogen chloride (512 ml.) andthe mixture hydrogenated at room temperature and pressure until thetheoretical amount of hydrogen was taken up. The mixture was filtered,the filtrate concentrated and ethyl acetate added to give ethyl2-amino-4-methyl-3-oxopentanoate hydrochloride (230.6 g.) m.p. 129°-131°C(dec.). This aminoketone (50.5 g.) was dissolved in redistilledformamide (180 ml.) and the solution heated at 120° for two hours, 130°for one hour, and finally at 140° for two hours. After cooling, themixture was filtered and the crystalline product washed with water togive ethyl 4-isopropyl-5-carbethoxy-imidazole (22. g.) m.p. 177°-178°.

This ester (108 g.) was placed in a soxhlet and reduced with lithiumaluminium hydride (34.5. g.) in tetrahydrofuran to give4-hydroxymethyl-5-isopropylimidazole (62.3 g.) m.p. 121°-123°.

ii. By a two-stage process essentially similar to that described inExample 58 (i) and (ii) there was produced from4-hydroxymethyl-5-isopropylimidazole firstly the intermediate4-isopropyl-5-[(2-aminoethyl)thiomethyl]-imidazole dipicrate (m.p.170°-172.5° C) and finally, after recrystallisation from isopropylacetate/ether the title compound, m.p. 86°-89° C.

EXAMPLE 61 Preparation of N-Methyl-N'-[2-(3-hydroxy-2-pyridyl)methylthio)ethyl]thiourea

By the method of Example 58 (i) and (ii)2-hydroxymethyl-3-hydroxy-pyridine was converted first to theintermediate 3-hydroxy-2-[(2-aminoethyl)thiomethyl]pyridinedihydrobromide (m.p. 231°-232° C.) and thence to the title compound(m.p. 130°-133° C., after recrystallisation from water).

EXAMPLE 62 Preparation ofN-methyl-N'-[2-(3-pyridazinyl)methylthio)-ethyl]thiourea.

By the method of Example 58 (i) and (ii) 3-hydroxymethylpyridazine wasconverted first to the intermediate3-[(2-aminoethyl)thiomethyl]-pyridazine dipicrate (m.p. 145°-148° C) andthence to the title compound (m.p. 110°-111° C, after recrystallisationfrom acetone/ether).

EXAMPLE 63 Preparation ofN-methyl-N'-[2-(5-(2-amino-1,3,4-thiadiazolyl)-methylthio)ethyl]thiourea

By the method of Example 58 (i) and (ii)2-amino-5-hydroxymethyl-1,3,4-thiadiazole was converted first to theintermediate 2-amino-5-[(2-aminoethyl)thiomethyl]-1,3,4-thiadiazoledibromide (m.p. 229°-232° C.) and thence to the title compound (m.p.143°-145° C, after recrystallisation from aqueous ethanol).

EXAMPLE 64 Preparation ofN-methyl-N'-[3-(4-imidazolylmethylthio)-propyl]thiourea

By the method of Example 58 (i) and (ii) 4(5)-hydroxymethylimidazole wasconverted first to the intermediate4(5)-[(3-aminopropyl)thiomethyl]-imidazole dihydrobromide and thence tothe title compound (m.p. 118°-120° C, after recrystallisation fromwater).

EXAMPLE 65 N-methyl-N'-[3-(2-oxazolyl)thiopropyl]thiourea

i. Hydrochloric acid (90 ml.) was added to potassium thiocyanate inethanol (1.8 l.) with stirring. Following filtration from inorganicmaterial, glycollaldehyde (35.9 g.) was added and the resulting solutionwas heated under reflux for 24 hours. Concentration, followed by coolingafforded a white solid, which following recrystallisation from ethanolafforded oxazole-2-thiol (30 g.), m.p. 143-4.

ii. 3-Bromopropylphthalimide (13.4 g.) was added to a stirred solutionof sodium ethoxide (from 1.15 g. sodium) and oxazole-2-thiol (5.1 g.) inethanol (100 ml.). The resultant solution was heated under reflux for2.5 hours and concentrated under reduced pressure. The residue wastriturated with water (100 ml.) to afford 2-(3-phthalimidopropylthio)oxazole (14. g) m.p. 101. Recrystallisation from ethanol gavethe pure oxazole m.p. 102-3.

ii. Hydrazine hydrate (5.3. g.) was added carefully to a solution of2-(3-phthalimidopropylthio)oxazole (10 g.) in ethanol (173 ml.) withstirring. The solution was then heated under reflux for 25 minutes.After cooling, and filtration from phthalhydrazide, the filtrate wasconcentrated under reduced pressure and the residue was re-evaporatedwith ethanol to yield crude 2-(3-aminopropylthio)oxazole which waswashed twice with ether and dissolved in ethanol (60 ml.). Methylisothiocyanate (2.54 g.) was added and the solution was heated underreflux for 30 minutes. Following cooling and filtration from insolublematerial, the filtrate was concentrated to an oil which waschromatographed on a column of silica gel with ethyl acetate as eluent.The product obtained crystallised from ethanol-ether-n-hexane to giveN-methyl-N'-[3-(2-oxazolyl)thiopropyl]thiourea (2.4 g), m.p. 43°-45°.

EXAMPLE 66 N-Methyl-N'-[2-(4-imidazolyl methoxy)ethyl]thiourea

i. A stirred suspension of 4-(2-chloroethoxy methyl) imidazolehydrochloride (14.7 g.) and sodium azide (9.8 g.) in drydimethylformamide (103 ml.) was maintained at 95° for 5 hours and thenset aside overnight at room temperature. Following dilution with waterand filtration, the filtrate was concentrated and the residue purifiedby chromatography on a dry column of alumina using ethanol. The productwas basified with potassium carbonate (6.5 g.) in water (3. ml.) and theanhydrous residue was extracted with isopropyl alcohol (3 × 50 ml.)Concentration of the extracts afforded 4-(2-azidoethoxymethyl)imidazole(7.2 g.) Hydrogenation of the azido compound (7.2 g.) in isopropylalcohol (142 ml.) over platinum oxide catalyst (3.0 g.) gave4-(2-aminoethoxy methyl)imidazole (6.48 g.) A sample of the monopicratemonohydrochloride had m.p. 139°-140° (from nitromethane).

(Found: C, 35.4; H, 3.8; N, 20.5; Cl, 8.8. C₁₂ H₁₅ ClN₆ O₈ requires: C,35.4; H, 3.7; N, 20.7; Cl, 8.7).

ii. 4-(2-Aminoethoxymethyl)imidazole (2.24 g.) was caused to react withmethylisothiocyanate (1.21 g.) in isopropyl alcohol (25 ml.) in theusual way. The crude product was purified by chromatography on a columnof silica gel with ethyl acetate as eluant and subsequently on a drycolumn of alumina, using chloroform. The final product wasrecrystallised from ethyl acetate to giveN-methyl-N'-[2-(4-imidazolylmethoxy)ethyl]thiourea (0.80 g.), m.p.96°-98°.

EXAMPLE 67 N-Methyl-N'-[3-(2-pyridylamino)propyl]thiourea

A solution of 2-(3-aminopropylamino)pyridine (2.74 g.) and methylisothiocyanate (1.46 g.) in isopropyl alcohol (50 ml.) was stirred atroom temperature for 16 hours. Concentration, followed by trituration ofthe residue under methyl ethyl ketone gave the crude product which, wasrecrystallized from aqueous ethanol to giveN-methyl-N'-[3-(2-pyridylamino)propyl]thiourea (2.45 g.) m.p.134°-135.5°.

EXAMPLE 68 N-methyl-N'-[2-((4-methyl-5-imidazolyl)methylthio)ethyl]urea

A mixture of 4-methyl-5-((2-aminoethyl)thiomethyl)imidazole (5.1 g.) andmethyl isocyanate (2.0 g.) in acetonitrile was heated for 18 hours in apressure vessel at 100°. After cooling, the solid obtained was collectedand recrystallised from isopropyl alcohol-acetonitrile to giveN-methyl-N'-[2-((4-methyl-5-imidazolyl) methylthio)ethyl]urea (4.0 g.)m.p. 158°-159°.

EXAMPLE 69 2-[(4-Imidazolyl)methylthio]ethylguanidine sulphate

A solution of 4-((2-aminoethyl)thiomethyl)imidazole (5.8 g.) andS-methyl isothiouronium sulphate (4.8 g.) in water (50 ml.) was heatedunder reflux for 3 hours. Following concentration to low bulk andacidification with dilute sulphuric acid, ethanol was added. The productobtained was recrystallised from aqueous methanol to give2-[(4-imidazolyl)methylthio]ethylguanidine sulphate (5.2 g.), m.p.211°-213°.

EXAMPLE 70N-(2-[(-4-methyl-5-imidazolyl)methylthio]ethyl)-N'-nitroguanidine

A solution of 4-methyl-5-(2-aminoethyl thiomethyl)imidazole (1.7 g.) andS-methyl-N-nitroisothiourea (1.45 g.) in methanol (35 ml.) was heated at50°-60° for 2.5 hours and then set aside at room temperature for 48hours. The crystalline product was filtered off and recrystallised frommethanol to give N-(2-[(4-methyl-5-imidazolyl)methylthio]ethyl)-N'-nitroguanidine, m.p. 184°-186°.

EXAMPLE 71 N-methyl-N'-[2-(4-trifluoromethyl-5-imidazolyl)methylthio)ethyl]thiourea

A mixture of ethyl 2-chloro-4,4,4-trifluoroacetate (65.7 g.), distilledformamide (135 g.) and water (11 ml.) was heated at 128°-130° for 1.5hours. After cooling, an equal volume of ice-cold water was added togive 4-trifluoromethyl-5-carbethoxyimidazole, m.p. 184°-186° (fromaqueous methanol).

Reduction of the ester (9.4 g.) with lithium aluminium bydride (2.4 g.)in tetrahydrofuran gave 5-hydroxymethyl-4-trifluoromethylimidazole,isolated at its picrate, m.p. 135.5°-137.5° (from aqueous isopropylalcohol).

The picrate (5.3 g.) was dissolved in 48% aqueous hydrobromic acid andextracted with toluene to remove picric acid. Cysteamine hydrochloride(1.52 g.) was added to the aqueous phase and the acidic solution heatedunder reflux for 12 hours. Concentration and trituration of the residuewith ethanol-ether gave4-trifluoromethyl-5-[(2-aminoethyl)thiomethyl]imidazole dihydrobromide(3.2 g.), m.p. 179°-182°. Basification followed by treatment with methylisothiocyanate gaveN-methyl-N'-[2-(4-trifluoromethyl-5-imidazolyl)methylthio)ethyl]thiourea.

EXAMPLE 72 N-methyl-N'-[2-(2-pyrimidyl)methylthio)ethyl]thiourea

A mixture of 5-bromo-2-hydroxymethylpyrimidine (5.6 g.) and magnesiumoxide (5.6 g.) in water/ethanol (2:1) was submitted to hydrogenolysisover 10% palladised charcoal for 0.5 hours. Filtration, concentrationand ether extraction from an aqueous solution of the residue afforded2-hydroxymethylpyrimidine (1.85 g.) as a mobile liquid.

The reaction of 2-hydroxymethylpyrimidine with cysteamine followed byfurther reaction of the product with methyl isothiocyanate, according tothe methods described in Example 58 gaveN-methyl-N'-[2-(2-pyrimidyl)methylthio)-ethyl]thiourea.

EXAMPLE 73 N-methyl-N'-[2-(2-pyrazinyl)methylthio)ethyl]thiourea

i. 2-chloromethylpyrazine (6.4 g.) was added over 20 minutes to asolution freshly prepared from sodium (0.23 g.) in ethanol (50 ml) towhich cysteamine hydrochloride (5.7 g.) had been added gradually at 0°and stirred at this temperature for 2 hours. The suspension finallyobtained was stirred at room temperature overnight, acidified withhydrochloric acid (pH 5) and concentrated under reduced pressure. Thedry residue was extracted with ethanol and the extracts filtered andconcentrated to give the crude product. Extraction with isopropylalcohol, with the removal of some polymeric material and the addition ofether gave a cream coloured solid (3.5 g.) which was recrystallised fromethanol-ether to furnish 2-[(2-aminoethyl)thiomethyl]pyrazinehydrochloride m.p. 144°-146°.

ii. The amine hydrochloride (1.6 g.) was converted into the free baseusing potassium carbonate and reacted with methyl isothiocyanate (0.61g.) in ethanol in the usual way. Recrystallisation from ethanolfurnished N-methyl-N'-[2-(2-pyrazinyl)methylthio)ethyl]thiourea (0.88g.) m.p. 99.5°-100°.

EXAMPLE 74 Preparation of N-methyl-N'-[2-((4-bromo-3-isothiazolyl)methylthio)ethyl]thiourea

The reaction of 4-bromo-3-(bromomethyl)isothiazole (8.5 g.) withcysteamine (from cysteamine hydrochloride (3.76 g) was performed underconditions similar to those described in Example 57. From the reactionthere was obtained 4-bromo-3-[(2-aminoethyl)thiomethyl]isothiazolehydrobromide, which, following recrystallisation from ethanol-ether andacetonitrile, gave needles (4.05 g.) m.p. 111°-112°. The amine base(2.73 g.) was isolated by basification with sodium bydroxide andextraction with chloroform and then dissolved in ethanol and treatedwith methyl isothiocyanate (0.78 g.) The solution was heated underreflux for 30 minutes, concentrated and the residue triturated withether to yield the crystalline thiourea (2.9 g.) m.p. 60°-61°.Recrystallisation from isopropyl acetate gaveN-methyl-N'-[2-((4-bromo-3-isothiazolyl)methylthio)ethyl]thiourea (2.3g.) as needles, m.p. 62°-63°.

EXAMPLE 75N-cyano-N'-methyl-N"-[2-((4-methyl-5-imidazolyl)methylthio)-ethyl]guanidine

A solution of 4-methyl-5-[(2-aminoethyl)thiomethyl]-imidazole (17.0 g.)and N-cyano-N',S-dimethylisothiourea (11.2 g.) in acetonitrile (500 ml)was heated under reflux for 24 hours. Following concentration, theresidue was chromatographed on a column of silica gel with acetonitrileas eluant and the product obtained was finally recrystallised fromacetonitrile-ether to yieldN-cyano-N'-methyl-N"-[2-((methyl-5-imidazolyl)methylthio)ethyl]guanidinem.p. 141°-2°.

WhenN-cyano-N'-methyl-N"-[2-((4-methyl-5-imidazolyl)-methylthio)ethyl]guanidineis treated with concentrated hydrochloric acid at 100° for 4 hours, theproduct which is recrystallised from ethanol-ether isN-methyl-N'-[2-((4-methyl-5-imidazolyl)methylthio)ethyl]guanidinedihydrochloride, m.p. 204°-206°.

(Found: C, 35.8; H, 6.5; N, 22.7; S, 10.8; Cl, 23.7. C₉ H₁₇ N₅ S.2HClrequires: C, 36.8; H, 6.4; N, 23.3; S, 10.7; Cl, 23.6).

EXAMPLE 76N-Cyano-N'-ethyl-N"-[2-((4-methyl-5-imidazolyl)methylthio)ethyl]guanidine

a. Anhydrous ethylamine (9.0 g) was added to a solution ofN-cyano-N'-[2-((4-methyl-5-imidazolyl)methylthio)ethyl]-S-methylisothiourea(5.0 g), prepared from 4-methyl-5-[(2-aminoethyl)thiomethyl]imidazole bythe procedure of Example 97, in ethanol. The solution was heated underreflux for 8 hours and concentrated under reduced pressure. The residuewas dissolved in isopropyl alcohol, filtered, and diluted with water.The white solid obtained was recrystallised from isopropyl alcohol-etherto yieldN-cyano-N'-ethyl-N"-[2-((4-methyl-5-imidazolyl)methylthio)ethyl]guanidine,m.p. 118°-120°.

(Found: C, 49.6; H, 6.8; N, 31.2; S, 11.7. C₁₁ H₁₈ N₆ S requires: C,49.6; H, 6.8; N, 31.6; S, 12.0).

b. (i) A solution of 4-methyl-5-[(2-aminoethyl)thiomethyl]-imidazole(6.9 g) and ethyl isothiocyanate (3.84 g) in ethanol was heated underreflux for 2 hours. Concentration followed by recrystallisation of theresidue from aqueous ethanol gaveN-ethyl-N'-[2-((4-methyl-5-imidazolyl)methylthio)ethyl]thiourea (9.0 g),m.p. 140°-141°.

(Found: C, 46.5; H, 7.1; N, 21.7; S, 25.1. C₁₀ H₁₈ N₄ S₂ requires: C,46.5; H, 7.0; N, 21.7; S, 24.8).

ii. Reaction of the thiourea with excess lead cyanamide by a proceduresimilar to that described in Example 91, refluxing for 24 hours,affordedN-cyano-N'-ethyl-N"-[2-((4-methyl-5-imidazolyl)methylthio)ethyl]guanidine.

EXAMPLE 77N-Cyano-N'-[2-((4-methyl-5-imidazolyl)methylthio)ethyl]-guanidine

A solution ofN-cyano-N'-[2-((4-methyl-5-imidazolyl)-methylthio)ethyl]-S-methylisothiourea(2.69 g) in saturated ammoniacal ethanol (100 ml) was heated in apressure vessel for 16 hours at 95°. Following concentration, theresidue was chromatographed on a column of silica gel with ethyl acetateas eluant and finally recrystallized from acetonitrile to giveN-cyano-N'-[2-((4-methyl-5-imidazolyl) methylthio)ethyl]guanidine (0.9g), m.p. 125°-127°.

(Found: C, 45.2; H, 5.9; N, 35.1; S, 13.3; C₉ H₁₄ N₆ S requires: C,45.4; H, 5.9; N, 35.3; S, 13.5).

EXAMPLE 78N-[2-((4-Bromo-5-imidazolyl)methylthio)ethyl]-N'-cyano-N"-methylguanidine

The sequential reaction of dimethyl-N-cyanoimidodithiocarbonate (0.99 g)with 4-bromo-5-[(2-aminoethyl)thiomethyl] imidazole (1.6 g), prepared bythe procedure of Example 58, and excess methylamine by the proceduredescribed in Example 98 affordedN-[2-((4-bromo-5-imidazolyl)methylthio)ethyl]-N'-cyano-N"-methylguanidine(1.45 g), m.p. 144°-146° (from nitromethane).

(Found: C, 34.3; H, 4.2; N, 26.7; S, 10.1; C₉ H₁₃ BrN₆ S requires: C,34.1; H, 4.1; N, 26.5; S, 10.2).

EXAMPLE 79N-[2-((2-Amino-4-imidazolyl)methylthio)ethyl]-N'-cyano-N"-methylguanidine

Freshly prepared sodium amalgam (90 g) is added over 75 minutes to astirred solution of serine ethyl ester dihydrochloride (3.0g) inwater/ethanol (2:1), the temperature being maintained within the rangeof from -12° to 10° and the pH at about 2.5 by the addition of 5Nhydrochloric acid. After a further 45 minutes the mixture is allowed towarm to 10° and the precipitated free mercury is removed. Cyanamide isadded and the mixture warmed to 50° for 30 minutes, left at 0° for 18hours and evaporated to dryness. After washing with ether to remove anyunchanged cyanamide, the residue is extracted with hot ethanol andheated with hot ethanolic picric acid. Concentration and cooling of thesolution gives 2-amino-4-hydroxymethylimidazole picrate.

Reaction of 2-amino-4-hydroxymethylimidazole hydrochloride (which isobtained by treating the picrate salt with hydrochloric acid) withcysteamine hydrochloride by the procedure of Example 58 gives2-amino-4-[(2-aminoethyl)-thiomethyl]imidazole.

By the procedure of Example 75,2-amino-4-[(2-aminoethyl)-thiomethyl]imidazole is reacted withN-cyano-N',S-dimethylisothiourea to give the title compound.

EXAMPLE 80

                  EXAMPLE 80                                                      ______________________________________                                        Ingredients                Amounts                                            N-Cyano-N'-methyl-N"-[2-((4-methyl-5-                                         imidazolyl)methylthio)ethyl]guanidine                                                                    150 mg.                                            Mepyramine                 75 mg.                                             Sucrose                    75 mg.                                             Starch                     25 mg.                                             Talc                       5 mg.                                              Stearic Acid               2 mg.                                              ______________________________________                                    

The ingredients are screened, mixed and filled into a hard gelatincapsule.

EXAMPLE 81

                  EXAMPLE 81                                                      ______________________________________                                         Ingredients               Amounts                                            ______________________________________                                        N-[2-((4-Methyl-5-imidazolyl)methylthio)-                                     ethyl]-N'-nitroguanidine   200 mg.                                            Mepyramine                 100 mg.                                            Lactose                    100 mg.                                            ______________________________________                                    

The ingredients are screened, mixed and filled into a hard gelatincapsule.

EXAMPLE 82

By the procedure of Example 58, using as the starting materials2-hydroxymethylthiazole and 4-hydroxymethylthiazole, were produced thefollowing intermediate amine salts:

2-[(2-aminoethyl)thiomethyl]thiazole dihydrobromide, m.p. 144°-147.5° C.

4-[(2-aminoethyl)thiomethyl]thiazole dihydrobromide, m.p. 197°-203° C.

These amine salts were converted to the free bases and reacted withS-methylisothiouronium sulphate by the procedure of Example 69 to givethe following products:

2-(2-thiazolylmethylthio)ethylguanidine sulphate

2-(4-thiazolylmethylthio)ethylguanidine sulphate.

EXAMPLE 83

Reaction of 2-[(2-aminoethyl)thiomethyl]thiazole withS-methyl-N-nitroisothiourea by the procedure of Example 70 givesN-nitro-N'-[2-(2-thiazolylmethylthio)ethyl]guanidine.

Also, reaction of the same starting material withN,S-dimethyl-N'-nitroisothiourea givesN-methyl-N'-nitro-N"-[2-(2-thiazolylmethylthio)ethyl]guanidine.

EXAMPLE 84N-Cyano-N'-methyl-N"-[2-(2-thiazolylmethylthio)ethyl]-guanidine

Reaction of [(2-aminoethyl)thiomethyl]thiazole (from the dihydrobromide20.2 g) with N-cyano-N',S-dimethylisothiourea (7.75 g) by a proceduresimilar to that described in Example 75, affordedN-cyano-N'-methyl-N"-[(2-(2-thiazolylmethylthio)ethyl]guanidine, m.p.120°-122.5°, following chromatography on silica gel with alcohol.

(Found: C, 42.3; H, 5.1; N, 27.2; S, 25.3. C₉ H₁₃ N₅ S₂ requires: C,42.3; H, 5.1; N, 27.4; S, 25.1). Hydrolysis ofN-cyano-N'-methyl-N"-[2-(2-thiazolylmethylthio)ethyl]guanidine bytreating with concentrated hydrochloric acid at 100° for 4 hours givesN-methyl-N'-[2-(2-thiazolylmethylthio)ethyl]guanidine dihydrochloride.

EXAMPLE 85

Reaction ofN-cyano-N'-[2-(2-thiazolylmethylthio)ethyl]-S-methylisothiourea,prepared by reacting 2-[(2-aminoethyl) thiomethyl]thiazole withdimethyl-N-cyanoimidothio carbonate in ethanol by the procedure ofExample 97, with ethylamine in ethanol under reflux for 8 hours givesN-cyano-N'-ethyl-N"-[2-(2-thiazolylmethylthio)ethyl]-guanidine.

Similarly, using propylamine the product isN-cyano-N'-propyl-N"-[2-(2-thiazolylmethylthio)ethyl]-guanidine.

EXAMPLE 86N-Cyano-N'-methyl-N"-[2-(5-thiazolylmethylthio)ethyl]-guanidine

i. The reaction of 5-hydroxymethylthiazole (2.01 g) with cysteaminehydrochloride (1.99 g) in aqueous hydrobromic acid by the methoddescribed in Example 58 gave 5-((2-aminoethyl)thiomethyl)thiazoledihydrobromide (4.85 g) m.p. 191°-4° (from methanol).

ii. The reaction of 5-((2-aminoethyl)thiomethyl)-thiazole (2.24 g) withmethyl isothiocyanate (0.94 g) in ethanol (10 ml) gave a thiourea whichwas purified by chromatography on a column of silica gel with ethylacetate as eluant. Recrystallisation from isopropyl acetate-methyl ethylketone-ether gave N-methyl-N'-[2-(5-thiazolylmethylthio)ethyl]thiourea(2.1 g) m.p. 86°-88°.

iii. The reaction ofN-methyl-N'-[2-(5-thiazolylmethylthio)ethyl]thiourea with lead cyanamideby the procedure of Example 91, refluxing for 24 hours gives the titlecompound.

EXAMPLE 87N-Cyano-N'-methyl-N"-[2-((2-amino-4-thiazolyl)methylthio)-ethyl]guanidine

i. A mixture of 2-amino-4-chloromethylthiazole hydrochloride (9.0 g) andcysteamine hydrochloride (5.53 g) in acetic acid (100 ml) was heatedunder reflux for 18 hours. The crude product obtained afterconcentration was treated with picric acid in ethanol to afford2-amino-4-[(2-aminoethyl)thiomethyl]thiazole dipicrate, m.p.approximately 200°-210° (from ethanol).

ii. The picrate was converted into the free base by addition ofhydrochloric acid, removal of picric acid by toluene extraction,basification with potassium carbonate and extraction of the aqueousresidue with ethanol-ether. Reaction of the base (1.89 g) with methylisothiocyanate (0.73 g) in ethanol (10 ml) gave the crude thiourea.Chromatography on a column of silica gel with ethyl acetate as eluant,followed by recrystallisation from isopropyl alcohol-isopropyl acetategave N-methyl-N'-[2-((2-amino-4-thiazolyl)methylthio)ethyl]thiourea (1.0g)., m.p. 136°-140°.

iii. Reaction ofN-methyl-N'-[2-((2-amino-4-thiazolyl)-methylthio)ethyl]thiourea withlead cyanamide by the procedure of Example 91, refluxing for 24 hours,gives the title compound.

EXAMPLE 88

The following hydroxymethyl and halomethyl thiazoles are converted tothe corresponding (2-amino-ethyl)thiomethylthiazoles by the procedure ofExample 58:

2-hydroxymethyl-4-methylthiazole

4-chloromethyl-2-methylthiazole

2-chloro-4-chloromethylthiazole

and using the (2-aminoethyl)thiomethylthiazoles as starting materials inthe procedure of Example 75 gives the following products, respectively:

N-cyano-N'-methyl-N"-[2-((4-methyl-2-thiazolyl)-methylthio)ethyl]guanidine

N-cyano-N'-methyl-N"-[2-((2-methyl-4-thiazolyl)-methylthio)ethyl]guanidine.

N-[2-((2-chloro-4-thiazolyl)methylthio)ethyl]-N-cyano-N"-methylguanidine.

EXAMPLE 89

2-Hydroxy-4-thiazolecarboxylic acid is converted to the methyl ester andthe ester is reduced with lithium aluminium hydride in tetrahydrofuranto give 2-hydroxy-4-hydroxymethylthiazole. By the procedure of Example58 this compound is converted to4-[(2-aminoethyl)thiomethyl]-2-hydroxythiazole. Using this compound asthe starting material in the procedure of Example 84 givesN-[2-((2-hydroxy-4-thiazolyl)methylthio)ethyl]-N-cyano-N"-methylguanidine.

                  EXAMPLE 90                                                      ______________________________________                                         Ingredients                Amounts                                           ______________________________________                                        N-cyano-N'-methyl-N"-[2-(2-thiazolyl-                                         methylthio)ethyl]guanidine 150 mg.                                            Mepyramine                 75 mg.                                             Sucrose                    75 mg.                                             Starch                     25 mg.                                             Talc                       5 mg.                                              Stearic acid               2 mg.                                              ______________________________________                                    

The ingredients are mixed and filled into a hard gelatin capsule.

EXAMPLE 91N-Cyano-N'-[2-(3-isothiazolylmethylthio)ethyl]-N"-methylguanidine

a. (i) A solution was prepared by the gradual addition of cysteaminehydrochloride (2.03 g) to sodium (0.83 g) dissolved in ethanol (50 ml)with stirring at 0° under a nitrogen atmosphere. After stirring for 2hours at 0°, 3-bromomethylisothiazole (3.2 g) was added dropwise over 15minutes at 0°, the reaction mixture subsequently being set asideovernight at room temperature. Following acidification to pH 3.5 withhydrochloric acid, concentration and re-evaporation with ethanol, theresidue was dissolved in ethanol, filtered and concentrated to yield3-[(2-aminoethyl)thiomethyl]isothiazole hydrochloride (3.5 g). This wasconverted directly to the free base by treatment with aqueous potassiumcarbonate and extraction with ether. The extracts were dried overmagnesium sulphate, filtered and concentrated to yield the amine base asan oil (1.56 g). The amine was dissolved in ethanol (10 ml), methylisothiocyanate (0.66 g) added, and the solution heated under reflux for30 minutes. Concentration, followed by purification of the crude productby chromatography on a column of silica gel with ethyl acetate as eluantfollowed by chromatography on a column of alumina with benzene/ethylacetate gave N-methyl-N' -[2-(3-isothiazolylmethylthio)ethyl]-thiourea.

(Found: C, 38.9; H, 5.4; N, 16.5; S, 38.3. C₈ H₁₃ N₃ S₃. requires: C,38.8; H, 5.3; N, 17.0; S, 38.9.)

ii. Lead cyanamide (52.6 g) was added to a solution ofN-methyl-N'-[2-(3-isothiazolylmethylthio)ethyl]thiourea (17.7 g) inacetonitrile (500 ml) containing dimethylformamide (50 ml). The mixturewas stirred under reflux for 48 hours, then filtered and concentrated.The product was chromatographed on silica gel with ethyl acetate aseluant and recrystallised from isopropyl acetate-ether to giveN-cyano-N'-[2-(3-isothiazolylmethylthio)ethyl]-N"-methylguanidine, in acrystalline form, m.p.. 63°-64°. Further recrystallisation fromisopropyl acetate afforded the cyanoguanidine in a crystalline form,m.p. 91°-92°.

(Found: C, 42.6; H, 5.2; N, 27.4; S, 25.4; C₉ H₁₃ N₅ S₂ requires: C,42.3; H, 5.1; N, 27.4; S, 25.1).

b. (i) The reaction of dimethyl-N-cyanoimidodithiocarbonate (1.50 g)with 3-[(2-aminoethyl)thiomethyl]isothiazole (1.70 g) affordedN-cyano-N'-[2-(3-isothiazolylmethylthio)-ethyl]-S-methylisothiourea.Recrystallisation from isopropyl acetate afforded 0.68 g, m.p. 85°-87°.

(Found: C, 39.7; H, 4.4; N, 20.6; S, 35.4; C₉ H₁₂ N₄ S₃ requires: C,39.7; H, 4.4; N, 20.6; S, 35.3).

ii. The reaction ofN-cyano-N'-[2-(3-isothiazolylmethylthio)ethyl]-S-methylisothiourea (0.27g) with excess methylamine and recrystallisation of the product fromisopropyl acetate affordedN-cyano-N'-[2-(3-isothiazolylmethylthio)ethyl]-N"-methylguanidine (0.12g), m.p. 91°-93°.

(Found: C, 42.4; H, 5.1; N, 27.3; S, 25.2; C₉ H₁₃ N₅ S₂ requires: C,42.3; H, 5.1; N, 27.3; S, 25.2;

EXAMPLE 92

The reaction of 4-bromo-3-(bromomethyl)isothiazole (8.5 g) withcysteamine (from cysteamine hydrochloride, 3.76 g) was performed underconditions similar to those described in Example 91. From the reactionthere was obtained 4-bromo-3-[(2-aminoethyl)thiomethyl]isothiazolehydrobromide, which, following recrystallisation from ethanol-ether andacetonitrile, gave needles (4.05 g) m.p. 111°-112°. The amine base (2.73g) was isolated by basification with sodium hydroxide and extractionwith chloroform and then dissolved in ethanol and treated with methylisothiocyanate (0.78 g). The solution was heated under reflux for 30minutes, concentrated and the residue triturated with ether to yield thecrystalline thiourea (2.9 g) m.p. 60°-61°. Recrystallisation fromisopropyl acetate gaveN-methyl-N'-[2-((4-bromo-3-isothiazolyl)methylthio)ethyl]thiourea (2.3g) as needles, m.p. 62°-63°: Reaction ofN-methyl-N'-[2-((4-bromo-3-isothiazolyl)-methylthio)ethyl]thiourea withlead cyanamide by the procedure of Example 91 givesN-cyano-N'-[2-((4-bromo-3-isothiazolyl)methylthio)ethyl]-N"-methylguanidine.Hydrolysis of the above product according to the procedure of Example 84gives N-[2-((4-bromo-3 -isothiazolyl)methylthio)ethyl]-N'-methylguanidine hydrochloride.

EXAMPLE 93

Reacting 4-hydroxymethyl-3-methylisothiazole (3.0 g) with cysteaminehydrochloride (2.8 g) in 48% aqueous hydrobromic acid (50 ml) by theprocedure of Example 58 gives3-methyl-4-[(2-aminoethyl)thiomethyl]-isothiazole hydrobromide.Treatment of this intermediate with aqueous potassium carbonate,extracting with chloroform, drying the chloroform extract over magnesiumsulphate and concentrating gives the free base, 5.0 g. of which is thenreacted with methyl isothiocyanate (1.94 g) in ethanol (25 ml) underreflux for 30 minutes. The product is purified on a column of aluminaand elution with benzene givesN-methyl-N'-[2-((3-methyl-4-isothiazolyl)methylthio)ethyl]thiourea.Reaction of this product by the procedure of Example 91 givesN-cyano-N'-methyl-N"-[2-((3-methyl-4-isothiazolyl)-methylthio)ethyl]guanidine.

Using 3-bromomethyl-5-chloroisothiazole as the starting material in theabove procedure, the product isN-[2-((5-chloro-3-isothiazolyl)methylthio)ethyl]-N'-cyano-N"-methylguanidine.

EXAMPLE 94 2-(3-Isothiazolylmethylthio)ethylguanidine sulphate

Reacting 3-[(2-aminoethyl)thiomethyl]isothiazole withS-methylisothiouronium sulphate by the procedure of Example 69 gives thetitle compound.

EXAMPLE 95

Reacting 3-[(2-aminoethyl)thiomethyl]isothiazole withS-methyl-N-nitroisothiourea by the procedure of Example 70 givesN-[2-(3-isothiazolymethylthio)ethyl]-N' -nitro-guanidine and reaction ofthe same starting material with N,S-dimethyl-N'-nitroisothiourea givesN-[2-(3-isothiazolylmethylthio)ethyl]-N' -methyl-N"-nitroguanidine.

                  EXAMPLE 96                                                      ______________________________________                                         Ingredients                Amounts                                           ______________________________________                                        N-cyano-N'-[2-(3-isothiazolylmethylthio)-                                     ethyl]-N"-methylguanidine  200 mg.                                            Mepyramine                 100 mg.                                            Lactose                    100 mg.                                            ______________________________________                                    

The ingredients are mixed and filled into a hard gelatine capsule.

EXAMPLE 97N-Cyano-N'-[2-((3-hydroxy-2-pyridyl)methylthio)ethyl]-N"-methylguanidine

i. A solution of 2-((2-aminoethyl)thiomethyl)-3-hydroxypyridine (7.5 g)in ethanol was added slowly to a solution ofdimethylcyanodithioimidocarbonate (6.0 g) in ethanol, with stirring atroom temperature. The mixture was set aside overnight at roomtemperature. Filtration affordedN-cyano-N'-[2-((3-hydroxy-2-pyridyl)methylthio)-ethyl]-S-methylisothiourea(4.85 g), m.p. 192°-194°. Recrystallisation from aqueous ethanol gavefine needles, m.p. 196°-198°.

(Found: C, 46.6.; H, 5.0; N, 19.8; S, 22.7; C₁₀ H₁₄ N₄ OS₂ requires: C,46.8; H, 5.0; N, 19.8; S,22.7.)

ii. A mixture ofN-cyano-N'-[2-((3-hydroxy-2-pyridyl)-methylthio)ethyl]-S-methylisothiourea(4.8 g) and excess methylamine in ethanol was allowed to stand at roomtemperature for 2.5 hours. Following concentration under reducedpressure, the residue was chromatographed on a column of silica gel withethyl acetate containing 15% isopropyl alcohol as eluant andrecrystallisation from isopropyl alcohol-petroleum ether gaveN-cyano-N'-[2-((3-hydroxy-2-pyridyl)methylthio)ethyl]-N"-methylguanidine(2.4 g), m.p. 146°-148°.

EXAMPLE 98 N-Cyano-N'-[2-((3-bromo-2-pyridyl)methylthio)ethyl]-N"-methylguanidine

i. A solution sodium nitrite (2.28 g) in water (10 ml) was addeddropwise to a stirred mixture of 3-amino-2-hydroxymethylpyridine (4.8 g)in aqueous hydrobromic acid (48%, 10 ml) and water (5 ml) at 0.5° C.This solution of the diazonium salt was added to a hot solution ofcuprous bromide (2.5 g) in 60% hydromic acid and following cessation ofnitrogen evolution the mixture was heated on the steam bath for 0.5hours, diluted with water and saturated with hydrogen sulphide.Filtration, concentration to low bulk and extraction with chloroformyielded 3-bromo-2-hydroxymethylpyridine (4.8 g). This was dissolved inaqueous hydrobromic acid (48%, 50 ml), cysteamine hydrochloride (3.22 g)added and the solution obtained was heated under reflux for 6 hours.Concentration, followed by recrystalliation from aqueous ethanolafforded 2-((2-aminoethyl)thiomethyl)-3-bromopyridine dihydrobromide(6.1 g), m.p. 252°-254°.

(Found: C, 23.7; H, 3.4; N, 6.7; S, 7.9; C₈ H₁₁ Br N₂ S.2HBr requires:C, 23.5; H, 3.2; N, 6.9; S, 7.8).

ii. Sequential reaction of dimethylcyanodithioimidocarbonate with2-((2-aminoethyl)thiomethyl)-3-bromopyridine) and excess methylamine atroom temperature in ethanol, the methylamine being added after initialstanding overnight and the solution then allowed to stand for a furtherfour hours, followed by chromatographic purification on a column ofsilica gel with elution by ethyl acetate and final recrystallisationfrom ethyl acetate-petroleum ether gaveN-cyano-N'-[2-((3-bromo-2-pyridyl)methylthio)ethyl]-N"-methylguanidinem.p. 114°-116°.

(Found: C, 40.6; H, 4.4; N, 21.4; S, 9.8. C₁₁ H₁₄ Br N₅ S. requires: C,40.3; H, 4.3; N, 21.3; S, 9.8).

EXAMPLE 99

N-Cyano-N'-[2-((3-bromo-2-pyridyl)methylthio)ethyl]-N"-ethylguanidine

Sequential reaction of dimethylcyanodithioimidocarbonate with2-((2-aminoethyl)thiomethyl)-3-bromopyridine and excess ethylamine,followed by chromatographic purification on a column of silica gel withelution by ethyl acetate and final recrystallisation from ethylacetate-petroleum ether affordedN-cyano-N'-[2-((3-bromo-2-pyridyl)methylthio)-ethyl]-N"-ethylguanidine,m.p. 123°-124°.

(Found: C, 42.2; H, 4.7; N, 20.5; S, 9.4; C₁₂ H₁₆ Br N₅ S. requires: C,42.1; H, 4.7; N, 20.5; S, 9.4).

EXAMPLE 100

Sequential reaction of the following amines;

a. 2-[(2-aminoethyl)thiomethyl]-3-aminopyridine.

b. 2-[(2-aminoethyl)thiomethyl]-3-methylpyridine.

c. 4-[(2-aminoethyl)thiomethyl]pyridine.

d. 2-[(2-aminoethyl)thiomethyl]-5-hydroxypyridine.

with dimethylcyanodithioimidocarbonate and then excess methylamineaccording to the method described in Example 98 (ii) yield respectivelythe following products:

a.N-cyano-N'-methyl-N"-[2-((3-amino-2-pyridyl)methylthio)-ethyl]guanidine

b.N-cyano-N'-methyl-N"-[2-((3-methyl-2-pyridyl)methylthio)-ethyl]guanidine.

c. N-cyano-N'-methyl-N"-[2-((4-pyridyl)methylthio)ethyl]-guanidine.

d.N-cyano-N'-methyl-N"-[2-((5-hydroxy-2-pyridyl)methylthio)-ethyl]guanidine.

EXAMPLE 101

                  EXAMPLE 101                                                     ______________________________________                                         Ingredients                Amounts                                           ______________________________________                                        N-cyano-N'-methyl-N"-[2-((3-hydroxy-2-                                        pyridyl)methylthio)ethyl]guanidine.                                                                      150 mg.                                            Mepyramine                 75 mg.                                             Sucrose                    75 mg.                                             Starch                     25 mg.                                             Talc                       5 mg.                                              Stearic Acid               2 mg.                                              ______________________________________                                    

The ingredients are screened, mixed and filled into a hard gelatincapsule.

EXAMPLE 102

                  EXAMPLE 102                                                     ______________________________________                                         Ingredients               Amounts                                            ______________________________________                                        N-cyano-N'-methyl-N"-[2-((3-bromo-2-                                          pyridyl)methylthio)ethyl]guanidine.                                                                     200 mg.                                             Mebrophenhydramine        100 mg.                                             Lactose                   100 mg.                                             ______________________________________                                    

The ingredients are screened, mixed and filled into a hard gelatincapsule.

What is claimed is:
 1. A pharmaceutical composition having H-1 and H-2histamine receptor inhibiting activity which comprises about 30 mg. toabout 250 mg. of an antihistamine, said antihistamine being a compoundwhich inhibits those histamine receptors inhibited by mepyramine, about50 mg. to about 500 mg. of an H-2 histamine receptor inhibitor, H-2histamine receptors being those histamine receptors which are notinhibited by mepyramine but are inhibited by burimamide, and apharmaceutically acceptable diluent or carrier, wherein said H-2histamine receptor inhibitor is a compound of the formula: ##STR15##wherein A is such that there is formed together with the carbon atomshown an imidazole ring; X₁ is hydrogen, lower alkyl, halogen, amino orhydroxyl; X₂ is hydrogen; k is 1; m is 2; Y is sulphur; E is NR₂ ; R₁ ishydrogen or lower alkyl; and R₂ is hydrogen, nitro or cyano,or apharmaceutically acceptable acid addition salt thereof.
 2. Apharmaceutical composition according to claim 1 wherein theantihistamine is a compound selected from the group consisting ofmepyramine, mebrophenhydramine, promethazine, diphenhydramine,chloropheniramine, triprolidene, antazoline, bromodiphenydramine,parabromdylamine, carbinoxamine, cyproheptadine, chlorcyclizine,dimethindene, diphenylpyraline, dimethothiazine, methdilazine,trimeprazine, mebhydroline, methapyrilene, phenindamine, pheniramine,phenyltoloxamine and pyrrobutamine.
 3. A pharmaceutical compositionaccording to claim 1 wherein the H-2 histamine receptor inhibitor is acompound selected from the group consisting ofN-cyano-N'-methyl-N"-[2-((4-methyl-5-imidazolyl)-methylthio)ethyl]guanidine,2-[(4-imidazolyl)methylthio]-ethylguanidine andN-(2-[(4-methyl-5-imidazolyl)methylthio]-ethyl)-N'-nitroguanidine.
 4. Apharmaceutical composition according to claim 1 wherein the H-2histamine receptor inhibitor isN-cyano-N'-methyl-N"-[2-((4-methyl-5-imidazolyl)methylthio)ethyl]guanidine5. A pharmaceutical composition according to claim 1, wherein theantihistamine is mepyramine and the H-2histamine receptor inhibitor isN-cyano-N'-methyl-N"-[2-((4-methyl-5-imidazolyl)methylthio)ethyl]guanidine.6. A method of inhibiting H-1 and H-2 histamine receptors whichcomprises administering to an animal in need thereof, in amountssufficient to inhibit both H-1 and H-2 histamine receptors, anantihistamine, said antihistamine being a compound which inhibits thosehistamine receptors inhibited by mepyramine, and an H-2 histaminereceptor inhibitor, said H-1 histamine receptors being those histaminereceptors which are inhibited by mepyramine and said H-2 histaminereceptors being those histamine receptors which are not inhibited bymepyramine but are inhibited by burimamide, wherein said H-2 histaminereceptor inhibitor is a compound of the formula: ##STR16## wherein A issuch that there is formed together with the carbon atom shown animidazole ring; X₁ is hydrogen, lower alkyl, halogen, amino or hydroxyl;X₂ is hydrogen; k is 1; m is 2; Y is sulphur; E is NR₂ ; R₁ is hydrogenor lower alkyl; and R₂ is hydrogen, nitro or cyano,or a pharmaceuticallyacceptable acid addition salt thereof.
 7. A method of claim 6 whereinthe antihistamine is a compound selected from the group consisting ofmepyramine, mebrophenhydramine, promethazine, diphenhydramine,chlorpheniramine, triprolidene, antazoline, bromodiphenydramine,parabromdylamine, carbinoxamine, cyproheptadine, chlorcyclizine,dimethindene, diphenylpyraline, dimethothiazine, methdilazine,trimeprazine, mebhydroline, methapyrilene, phenindamine, pheniramine,phenyltoloxamine and pyrrobutamine.
 8. A method of claim 6 wherein theH-2 histamine receptor inhibitor is selected from the group consistingofN-cyano-N'-methyl-N"-[2-((4-methyl-5-imidazolyl)methylthio)ethyl]guanidine,2-[(4-imidazolyl)methylthio]ethylguanidine andN-(2-[(4-methyl-5-imidazolyl)methylthio]ethyl)-N'-nitroguanidine.
 9. Amethod of claim 6 wherein the H-2 histamine receptor inhibitor isN-cyano-N'-methyl-N"-[2-((4-methyl-5-imidazolyl)methylthio)ethyl]guanidine.10. The method of claim 6 wherein the antihistamine is mepyramine andthe H-2 histamine receptor inhibitor isN-cyano-N'-methyl-N"-[2-((4-methyl-5-imidazolyl)methylthio)ethyl]guanidine.
 11. A method of producing anti-inflammatory activitywhich comprises administering to an animal in need thereof, in amountssufficient to produce said activity, an antihistamine, saidantihistamine being a compound which inhibits those histamine receptorsinhibited by mepyramine, and an H-2 histamine receptor inhibitor, saidH-2 histamine receptors being those histamine receptors which are notinhibited by mepyramine but are inhibited by burimamide, wherein saidH-2 -histamine receptor inhibitor is a compound of the formula:##STR17## wherein A is such that there is formed together with thecarbon atom shown an imidazole ring; X₁ is hydrogen, lower alkyl,halogen, amino or hydroxyl; X₂ is hydrogen; k is 1; m is 2; Y issulphur; E is NR₂ ; R₁ is hydrogen or lower alkyl; and R₂ is hydrogen,nitro or cyano,or a pharmaceutically acceptable acid addition saltthereof.
 12. A method of claim 11 in which the antihistamine is acompound selected from the group consisting of mepyramine,mebrophenhydramine, promethazine, diphenhydramine, chlorpheniramine,triprolidene, antazoline, bromodiphenhydramine, parabromdylamine,carbinoxamine, cyproheptadine, chlorcyclizine, dimethindene,diphenylpyraline, dimethothiazine, methdilazine, trimeprazine,mebhydroline, methapyrilene, phenindamine, pheniramine, phenyltoloxamineand pyrrobutamine.
 13. A method of claim 11 wherein the H-2 histaminereceptor inhibitor is selected from the group consisting ofN-cyano-N'-methyl-N"-[2-((4-methyl-5-imidazolyl)methylthio)ethyl]guanidine,2-[(4-imidazolyl)methylthio]ethylguanidineand N-(2-[(4-methyl-5-imidazolyl)methylthio]ethyl)-N'-nitroguanidine.14. A method of claim 11 wherein the H-2 histamine receptor inhibitor isN-cyano-N'-methyl-N"-[2-((4-methyl-5-imidazolyl)methylthio)ethyl]guanidine.15. A method of claim 11 wherein the antihistamine is mepyramine and theH-2 histamine receptor inhibitor isN-cyano-N'-methyl-N"-[2-((4-methyl-5-imidazolyl)methylthio)-ethyl]guanidine16. A pharmaceutical composition having H-1 and H-2 histamine receptorinhibiting activity which comprises about 30 mg. to about 250 mg. of anantihistamine, said antihistamine being a compound which inhibits thosehistamine receptors inhibited by mepyramine, about 50 mg. to about 500mg. of an H-2 histamine receptor inhibitor, H-2histamine receptors beingthose histamine receptors which are not inhibited by mepyramine but areinhibited by burimamide, and a pharmaceutically acceptable diluent orcarrier, wherein said H-2 histamine receptor inhibitor is4-(3-guanidinopropyl)imidazole or a pharmaceutically acceptable acidaddition salt thereof.
 17. A method of inhibiting H-1 and H-2 histaminereceptors which comprises administering to an animal in need thereof, inamounts sufficient to inhibit both H-1 and H-2 histamine receptors, anantihistamine, said antihistamine being a compound which inhibits thosehistamine receptors inhibited by mepyramine, and an H-2 histaminereceptor inhibitor, said H-1 histamine receptors being those histaminereceptors which are inhibited by mepyramine and said H-2 histaminereceptors being those histamine receptors which are not inhibited bymepyramine but are inhibited by burimamide, wherein said H-2 histaminereceptor inhibitor is 4-(3-guanidinopropyl)imidazole or apharmaceutically acceptable acid addition salt thereof.
 18. A method ofproducing anti-inflammatory activity which comprises administering to ananimal in need thereof, in amounts sufficient to produce said acitivity,an antihistamine, said antihistamine being a compound which inhibitsthose histamine receptors inhibited by mepyramine, and an H-2 histaminereceptor inhibitor, said H-2 histamine receptors being those histaminereceptors which are not inhibited by mepyramine but are inhibited byburimamide, wherein said H-2 histamine receptor inhibitor is4-(3-guanidinopropyl)imidazole or a pharmaceutically acceptable acidaddition salt thereof.